AES London 2011
Paper Session Details

 

P1 - Speech and Hearing


Friday, May 13, 09:30 — 12:30 (Room 4)

Chair:
Robert Schulein

P1-1 The Evolution of the Speech Transmission IndexHerman J. M. Steeneken, TNO Human Factors (retired) - Soesterberg, The Netherlands, Embedded Acoustics, Delft, The Netherlands; Sander J. van Wijngaarden, Jan A. Verhave, Embedded Acoustics - Delft, The Netherlands
This year, the Speech Transmission Index celebrates its 40th anniversary. While the first measuring device built in the 1970s could barely fit inside a car, inexpensive pocket-size STI measuring solutions are now available to the world. Meanwhile, the STI method has continually evolved in order to deal with an increasing array of measuring challenges. This paper investigates how the STI kept up with these challenges and analyzes possible room for further improvement. Also, a roadmap for further development of the STI is proposed.
Convention Paper 8315 (Purchase now)

P1-2 Prosody Generation Module for Macedonian Text-to-Speech SynthesisBranislav Gerazov, Zoran Ivanovski, Faculty of Electrical Engineering and Information Technologies - Skopje, Macedonia
The paper presents a fully functional prosody generation module developed for Macedonian text-to-speech (TTS) synthesis. The module is based on research of prosody generation modules in high-end TTS synthesis systems, previous prosody experiences in Macedonian TTS, as well as original research of prosody carried through by the authors. The paper starts with an overview of the basic tasks, problems, and solutions in prosody generation modules. Then it continues to give a detailed account of the workings of the developed module. The module first segments the input speech into intonation phrases, and determines their intonation type. Next it generates durations for each of the units that will be used to synthesize the speech output. Then it determines the positions of the lexical stresses and modifies these units’ durations. After determining the intonation phrase’s pitch accent location, it generates an adequate pitch contour and calculates the pitch targets needed for unit modification. The synthesis module uses this data to generate prosody in the output speech. Generated prosody patterns in the output speech are of satisfactory quality for arbitrary text input. The presented results are of significant value for Macedonian TTS and can be used for other underrepresented languages.
Convention Paper 8316 (Purchase now)

P1-3 The Influence of Transmission Channel on the Admissibility of Speech Sample for Forensic Speaker IdentificationAndrey Barinov, Speech Technology Center Ltd. - St. Petersburg, Russia
This paper is an extension and addition to papers previously published and presented during the AES 39th conference and AES 129th Convention, regarding voice sample quality requirements and compensation for the influence of transmission channels for further forensic or automatic speaker identification. In this paper we provide the analysis of different types of transmission channels such as land line, GSM, radio, and VoIP. We analyze the important parameters of voice samples obtained from these channels and compare the influence of different channels on important speaker identification voice biometric features. At the end of the paper, there are some conclusions provided regarding the circumstances under which the particular recording can be accepted / rejected for forensic speaker identification.
Convention Paper 8317 (Purchase now)

P1-4 Optimizing the Acoustic and Intelligibility Performance of Assistive Audio Systems and Program Relay for the Hard of Hearing and Other UsersPeter Mapp, Peter Mapp Associates - Colchester, Essex, UK
Around 10 % of the general population suffer from a noticeable degree of hearing loss and would benefit from some form of hearing assistance or deaf aid. DDA legislation and requirements mean that many more hearing assistive systems are being installed – yet there is continuing evidence to suggest that many of these systems fail to perform adequately and provide the benefit expected [1]. This paper reports on the results of acoustic performance testing of a number of trial ALS systems. The use of STIPA, as a practical measure for assessing the potential intelligibility of ALS systems, is discussed. The ALS microphone type, distance and angular location from the target acoustic source are shown to have a significant effect on the resultant potential intelligibility performance. The effects of typical ALS signal processing have been investigated and are shown to have a small but significant effect on the STIPA result. The requirements for a suitable acoustic test source to mimic a human talker are discussed as is the need to adequately assess the effects of both reverberation and noise. The findings of this paper are also relevant to the installation and testing of educational sound field systems as well as boardroom and conference room systems.
Convention Paper 8318 (Purchase now)

P1-5 Sound Reproduction within a Closed Ear Canal:Acoustical and Physiological EffectsSamuel Gido, Asius Technologies LLC - Longmont, CO, USA, University of Massachusetts, Amherst, MA, USA; Robert Schulein, Stephen Ambrose, Asius Technologies LLC - Longmont, CO, USA
When a sound producing device such as insert earphones or a hearing aid is sealed in the ear canal, the fact that only a tiny segment of the sound wave can exist in this small volume at any given instant, produces an oscillation of the static pressure in the ear canal. This effect can greatly boost the SPL in the ear canal, especially at low frequencies, a phenomena that we call Trapped Volume Insertion Gain (TVIG). In this study the TVIG has been found by numerical modeling as well as direct measurements using a Zwislocki coupler and the ear of a human subject, to be as much as 50 dB greater than sound pressures typically generated while listening to sounds in an open environment. Even at moderate listening volumes, the TVIG can increase the low frequency SPL in the ear canal to levels where they produce excursions of the tympanic membrane that are 100 to 1000 times greater than in normal open-ear hearing. Additionally, the high SPL at low frequencies in the trapped volume of the ear canal, can easily exceed the threshold necessary to trigger the Stapedius reflex, a stiffing response of the middle ear, which reduces its sensitivity and may lead to audio fatigue. The addition of a compliant membrane covered vent in the sound tube of an insert ear tip was found to reduce the TVIG by up to 20 dB, such that the Stapedius reflex would likely not be triggered.
Convention Paper 8319 (Purchase now)

P1-6 Can We Compare the Sound Quality of Noise Reduction between Hearing Aids? A Method to Level the Ground between DevicesRolph Houben, Inge Brons, Wouter A. Dreschler, Academic Medical Center, Amsterdam, The Netherlands
This paper proposes the application of an equalization filter to remove unwanted differences in frequency response between recordings from different hearing aids. The filter makes it possible to compare the perceptual effects (such as user preference) of a specific signal processing feature (e.g., noise reduction) between different hearing aids, without the dominant influence of differences in their frequency responses. Both an objective quality measure (PESQ) and a listening experiment have shown that the filter was able to “level the ground” between the devices included. The potential application of the inverse filter is to use it on recordings from hearing aids so that we can directly compare the noise reduction between devices. This allows one to determine if users prefer a certain noise reduction over another, which could lead to improved rehabilitation of hearing impaired listeners.
Convention Paper 8320 (Purchase now)

P2 - Loudspeakers


Friday, May 13, 09:30 — 12:30 (Room 1)

Chair:
John Vanderkooy

P2-1 Vibrations in the Loudspeaker Enclosure Evaluated by Hot Wire Anemometry and Laser InterferometryDanijel Djurek, AVAC (Alessandro Volta Applied Ceramics) Laboratory for Nonlinear Dynamics - Zlatar-Bistrica, Croatia; Nazif Demoli, Institute of Physics - Zagreb, Croatia
Vibration states of the loudspeaker enclosure were examined by the laser interferometry and hot wire anemometry. According to simple expressions, air pressure in the enclosure is independent on air density. This statement has been tested by the use of gases indicated by very different densities (air, He, SF6), and interferometric data show a strong dependence of vibration states of the enclosure walls on density, when driving frequency increases from 500 Hz up to 1 kHz. The main reason for a deviation resides in the imaginary part of the Morse impedance exerted by the vibrating gas within the enclosure.
Convention Paper 8321 (Purchase now)

P2-2 Losses and Coupling in Long Multi-Wire Loudspeaker CablesXavier Meynial, Guennolé Gapihan, Active Audio - Saint-Herblain, France
It is quite frequent in PA systems to use very long loudspeaker cables. These PA systems sometimes carry several audio signals in adjacent wires of the same cable, or several cables may be neighboring over very long distances such as several hundreds meters. This paper deals with losses and coupling in these long cables. It is shown that even though losses and coupling may introduce significant crosstalk between wires and affect the amplifier loads, it is possible to use very long loudspeaker cables to connect line arrays in PA systems. Coupling between cables is also investigated, and strategies for reducing losses and coupling are presented.
Convention Paper 8322 (Purchase now)

P2-3 Subwoofers in Rooms: Modal Analysis for Loudspeaker PlacementJuha Backman, Nokia Corporation - Espoo, Finland, Aalto University, Espoo, Finland
Use of multiple subwoofers in a room is known to help in reducing the variation of response both as a function of frequency and a function of place, but simple geometry-based placement rules guarantee good results only in symmetrical cases. The paper discusses the use of experimental modal analysis and numerical optimization based on modal behavior to determine the optimal placement of single or multiple subwoofers in rooms with arbitrary geometry and surface properties.
Convention Paper 8323 (Purchase now)

P2-4 Losses in Loudspeaker EnclosuresClaus Futtrup, Scan Speak A/S - Videbæk, Denmark
In recent papers a lumped parameter model, which can simulate the impedance of conventional electro-dynamic transducers accurately has been presented. The new model includes frequency-dependent damping, which questions traditional engineering practices in simulations of loudspeaker enclosures and, in particular, associated losses. In this paper the consequences of frequency-dependent damping are evaluated to aid the development of simulations and models of loudspeaker enclosures.
Convention Paper 8324 (Purchase now)

P2-5 Comparison of Measurement Methods for the Equalization of Loudspeaker Panels Based on Bending Wave RadiationLars Hörchens, Diemer de Vries, Delft University of Technology - Delft, The Netherlands
Spatially extended panel loudspeakers based on bending wave radiation, such as distributed mode loudspeakers or multi-actuator panels, exhibit a complex radiation pattern with frequency-dependent directivity characteristics. This paper seeks to determine the kind, position, and number of measurements needed to obtain an average radiation spectrum enabling efficient equalization. To this end, three approaches are compared: wave field extrapolation of the panel surface normal velocity, extrapolation of a near-field pressure measurement, and actual in-situ measurements at a number of random positions inside the listening space. The choice of the positions and the required number of measurements are discussed. Measurements taken on a multi-actuator panel are used to compare the different approaches and present numerical results.
Convention Paper 8325 (Purchase now)

P2-6 The Effect of Finite-Sized Baffles on Mobile Device Personal AudioJordan Cheer, Stephen J. Elliott, University of Southampton - Southampton, UK; Youngtae Kim, Jung-Woo Choi, Samsung Electronics Co. Ltd. - Korea
To reduce the annoyance from the use of loudspeakers on mobile devices, previous work has investigated the use of acoustic contrast control to optimize the performance of small arrays of loudspeakers. These investigations have assumed that the baffle dimensions are negligible so that the loudspeakers are omnidirectional, which is reasonable at low frequencies; however, in practice the effect of a finite-sized baffle on the optimized performance is important at higher frequencies. This paper reports the results of using a finite-element model of a two-source array, positioned on a mobile phone sized baffle, to investigate the influence of the baffle on the predicted array performance. The baffle is shown to reduce the performance of the array at frequencies greater than around 1 kHz, but then the directivity of the individual drivers enhances performance at these higher frequencies.
Convention Paper 8326 (Purchase now)

P3 - Sound Field Analysis


Friday, May 13, 11:00 — 12:30 (Room: Foyer)

P3-1 Localization of Multiple Speech Sources Using Distributed MicrophonesMaximo Cobos, Amparo Marti, Jose J. Lopez, Universidad Politecnica Valencia - Valencia, Spain
Source localization is an important task in many speech processing systems. There are many microphone array techniques intended to provide accurate source localization, but their performance is severely affected by noise and reverberation. The Steered-Response Power Phase Transform (SRP-PHAT) algorithm has been shown to perform very robustly in adverse acoustic environments; however, its computational cost can be an issue. Recently, the authors presented a modified version of the SRP-PHAT algorithm that improves its performance without adding a significant cost. However, the performance of the modified algorithm has only been analyzed in single source localization tasks. This paper explores further the possibilities of this localization method by considering multiple speech sources simultaneously active. Experiments considering different number of sources and acoustic environments are presented using simulations and real data.
Convention Paper 8327 (Purchase now)

P3-2 Detection of “Solo Intervals” in Multiple Microphone Multiple Source Audio ApplicationsElias Kokkinis, University of Patras - Patras, Greece; Joshua Reiss, Queen Mary University of London - London, UK; John Mourjopoulos, University of Patras - Patras, Greece
In this paper a simple and effective method is proposed to detect time intervals where only a single source is active (solo intervals) for multiple microphone, multiple source settings commonly encountered in audio applications, such as live sound reinforcement. The proposed method is based on the short term energy ratios between all available microphone signals, and a single threshold value is used to determine if and which source is solely active. The method is computationally efficient and results indicate that it is accurate and fairly robust with respect to reverberation time and amount of source interference.
Convention Paper 8328 (Purchase now)

P3-3 A Real-Time Sound Source Localization and Enhancement System Using Distributed MicrophonesAmparo Marti, Maximo Cobos, Jose J. Lopez, Universidad Politecnica Valencia - Valencia, Spain
The Steered Response Power - Phase Transform (SRP-PHAT) algorithm has been shown to be one of the most robust sound source localization approaches operating in noisy and reverberant environments. A recently proposed modified SRP-PHAT algorithm has been shown to provide robust localization performance in indoor environments without the need for having a very fine spatial grid, thus reducing the computational cost required in a practical implementation. Sound source localization methods are commonly employed in many sound processing applications. In our case, we use the modified SRP-PHAT functional for improving noisy speech signals. The estimated position of the speaker is used to calculate the time-delay for each microphone and then the speech is enhanced by aligning correctly the microphone signals.
Convention Paper 8329 (Purchase now)

P3-4 Binaural Moving Sound Source Localization by Joint Estimation of ITD and ILDCheng Zhou, Ruimin Hu, Weiping Tu, Xiaochen Wang, Li Gao, Wuhan University - Wuhan, Hubei, China
Spatial cues ITD and ILD that provide sound localization information play a very important role in the binaural localization system. The efficient improvement of binaural moving sound source localization method by joint estimation of ITD and ILD based on Doppler effect is investigated. By removing Doppler effect influence, results show that the proposed binaural moving sound source localization method achieves 0.3%(velocity = 1m/s), 5.7%(velocity = 5m/s), and 10.5%(velocity = 10m/s) accuracy improvement in silent conditions. The performance of our method will be more effective as sound moves faster.
Convention Paper 8330 (Purchase now)

P3-5 Perceived Level of Late Reverberation in Speech and MusicJouni Paulus, Christian Uhle, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Jürgen Herre, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany, International Audio Laboratories Erlangen, Erlangen, Germany
This paper presents experimental investigations on the perceived level of running reverberation in various types of monophonic audio signals. The design and results of three listening tests are discussed. The tests focus on the influence of the input material, the direct-to-reverberation ratio, and the reverberation time using artificially generated impulse responses for simulating the late reverberation. Furthermore, a comparison between mono and stereo reverberation is conducted. It can be observed that with equal mixing levels, the input material and the shape of the reverberation tail have a prominent effect on the perceived level. The results suggest that mono and stereo reverberation with identical reverberation times and mixing ratios are perceived as having equal level regardless of the material.
Convention Paper 8331 (Purchase now)

P3-6 Reverberation Enhancement in a Modal Sound FieldHugh Hopper, David Thompson, Keith Holland, University of Southampton - Hampshire, UK
The reverberation time of a room can be increased by using a reverberation enhancement system. These electronic systems have generally been installed in large rooms, where diffuse field assumptions are sufficiently accurate. Novel applications of the technology can be found by applying it to smaller spaces where isolated modal resonances will dominate at low frequency. An analysis of a multichannel feedback system within a rectangular enclosure is presented. To assess the performance of this system, metrics are defined based on the spatial and frequency variations of a diffuse field. These metrics are then used to optimize the parameters of the system using a genetic algorithm. It is shown that optimization significantly improves the performance of the system.
Convention Paper 8332 (Purchase now)

P3-7 An Advanced Implementation of a Digital Artificial ReverberatorAndrea Primavera, Stefania Cecchi, Laura Romoli, Paolo Peretti, Francesco Piazza, Universita Politecnica delle Marche - Ancona, Italy
Reverberation is a well known effect particularly important for listening of recorded and live music. In this paper we propose a real implementation of an enhanced approach for a digital artificial reverberator. Starting from a preliminary analysis of the mixing time, the selected impulse response is decomposed in the time domain considering the early and late reflections. Therefore, a short FIR is used to synthesize the first part of the impulse response, and a generalized recursive structure is used to synthesize the late reflections, exploiting a minimization criterion in the cepstral domain. Several results are reported taking into consideration different real impulse responses and comparing the results with those obtained with previous techniques in terms of computational complexity and reverberation quality.
Convention Paper 8333 (Purchase now)

P3-8 Evaluation of Spatial Impression Comparing 2-Channel Stereo, 5-Channel Surround, and 7-Channel Surround with Height Channels for 3-D ImageryToru Kamekawa, Atsushi Marui, Tokyo University of the Arts - Tokyo, Japan; Toshikiko Date, AVC Networks Company, Panasonic Corporation - Osaka, Japan; Masaaki Enatsu, marimoRECORDS Inc. - Tokyo, Japan
Three-dimensional (3-D) imagery is now widely spreading as one of the next visual formats for Blu-ray or other future media. Since more audio channels are available with future media, the authors aim to find the suitable sound format for 3-D imagery. A pairwise comparison test was carried out comparing combinations of 3-D and 2-D imagery with 2-channel stereo, 5-channel surround and 7-channel surround sound (5 channel surround plus 2 height channels) asking better depth sense and better match between visual and audio images. The results show that 3-D imagery with 7 channel surround gives the highest sense of depth and match of visual and audio images.
Convention Paper 8334 (Purchase now)

P4 - Multichannel/Spatial, Part 1


Friday, May 13, 14:00 — 17:00 (Room 1)

Chair:
Francis Rumsey

P4-1 3-D-Sound in Car Compartments Based on Loudspeaker Reproduction Using Crosstalk CancellationAndre Lundkvist, Arne Nykänen, Roger Johnsson, Luleå University of Technology - Luleå, Sweden
One way to enhance driving safety is to use signal sounds. Driver attention may further be improved by placing sounds in a 3-D space, using binaural synthesis. For correct loudspeaker reproduction of binaural signals, crosstalk between the channels needs to be canceled out. In this study, a crosstalk cancellation algorithm was developed and tested. The algorithm was applied in a car compartment, and three loudspeaker positions were compared. A listening test was performed to determine the subjects' ability to correctly localize sounds. It was shown that loudspeakers placed behind the listener correctly reproduced sound sources in the back hemisphere. Loudspeakers located in front and above the listener gave a high number of front/back confusions for all angles.
Convention Paper 8335 (Purchase now)

P4-2 Design of a Compact Cylindrical Loudspeaker Array for Spatial Sound ReproductionMihailo Kolundzija, Christof Faller, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland; Martin Vetterli, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland, University of California at Berkeley, Berkeley, CA, USA
Building acoustic beamformers is a problem whose solution is hindered by the wide-band nature of the audible sound. In order to achieve a consistent directional response over a wide range of frequencies, a conventional acoustic beamformer needs a high number of discrete loudspeakers and be large enough to achieve a desired low-frequency performance. The acoustic beamformer design described in this paper uses measurement-based optimal beamforming for loudspeakers located mounted on a rigid cylindrical baffle. Super-directional beamforming enables achieving desired directivity with multiple loudspeakers at low frequencies. High frequencies are reproduced with a single loudspeaker, whose highly directional reproduction—due to the cylindrical baffle—matches the design goals. In addition to the beamformer filter design procedure, it is shown how such loudspeaker array can be used for spatial sound reproduction.
Convention Paper 8336 (Purchase now)

P4-3 A New Multichannel Microphone Technique for Effective Perspective ControlHyunkook Lee, University of Huddersfield - Huddersfield, UK
This paper introduces a new multichannel microphone technique that was designed to produce multiple listener perspectives. A listener perspective paradigm and the related spatial attributes are also proposed for the evaluation of spatial quality in acoustic recording and reproduction. The proposed microphone array employs five coincident microphone pairs, which can be transformed into virtual microphones with different polar patterns and directions depending on the mixing ratio. The results of interchannel correlation and informal subjective evaluations suggest that the proposed technique is able to offer an effective control over various spatial attributes.
Convention Paper 8337 (Purchase now)

P4-4 Experimental Analysis of Spatial Properties of the Sound Field Inside a Car Employing a Spherical Microphone ArrayMarco Binelli, Andrea Venturi, Alberto Amendola, Angelo Farina, University of Parma - Parma, Italy
A 32-capsule spherical microphone array was employed for analyzing the spatial properties of the sound field inside a car. Both the background noise and the sound generated by the car's sound system were spatially analyzed, by superposing false-color sound pressure level maps over a panoramic 360x180 degree image, obtained with a parabolic-mirror camera. The analysis of the noise field revealed the parts of the car body where more noise is leaking in, providing guidance for better soundproofing. The analysis of the impulse responses generated by the loudspeakers did show useful information on the reflection patterns, providing guidance for adding absorbent material in selected locations and for optimizing position and orientation of loudspeakers.
Convention Paper 8338 (Purchase now)

P4-5 Improved ITU and Matrix Surround DownmixingChristof Faller, Illusonic LLC - St-Sulpice, Swtizerland; Pieter Schillebeeckx, Soundfield Ltd. - Wakefield, UK
Improvements to ITU and matrix surround downmixing are proposed. The surround channels are often mixed into the downmix with reduced gain to prevent that the resulting stereo signal is overly ambient. A method is proposed that allows control of the amount of ambience in the downmix signal independently of direct sound. In a conventional matrix surround downmix, ambience from the surround channels appears impaired (negatively correlated) . To address this issue, a technique is proposed that separates direct and ambient sound. Then, a matrix surround downmix is only applied to the direct sound, while ambient sound is treated like in an ITU downmix.
Convention Paper 8339 (Purchase now)

P4-6 Spaciousness Rating of 8-Channel Stereophony-Based Microphone ArraysLaurent Simon, University of Surrey - Guildford, Surrey, UK (now with INRIA – Rennes, Bretagne Atlantique, France); Russell Mason, University of Surrey - Guildford, Surrey, UK
In previous studies, the localization accuracy and the spatial impression of 3-2 stereo microphone arrays were discussed. These showed that 3-2 stereo cannot produce stable images to the side and to the rear of the listener. An octagon loudspeaker array was therefore proposed. Microphone array design for this loudspeaker configuration was studied in terms of localization accuracy, locatedness, and image width. This paper describes an experiment conducted to evaluate the spaciousness of 10 different microphone arrays used in different acoustical environments. Spaciousness was analyzed as a function of sound signal, acoustical environment, and microphone array's characteristics. It showed that the height of the microphone array and the original acoustical environment are the two variables that have the most influence on the perceived spaciousness, but that microphone directivity and the position of sound sources is also important.
Convention Paper 8340 (Purchase now)

P5 - Production and Broadcast


Friday, May 13, 14:00 — 17:30 (Room 4)

Chair:
Natanya Ford

P5-1 Frequency Weighting and Ballistics for Program Loudness ModelingIan M. Dash, Australian Broadcasting Corporation - Sydney, NSW, Australia; Benjamin Smith, Densil Cabrera, University of Sydney - Sydney, NSW, Australia
There has been both experimental and anecdotal evidence that the low-frequency performance in the ITU-R Recommendation BS.1770 program loudness measurement algorithm could be improved. A listening test with an emphasis on low frequency content was therefore conducted. An attempt was made to analyze the results in octave bands by multiple regression, but larger than expected variability precluded any useful outcome from this method. A simpler regression analysis was therefore performed using several fixed weighting curves and asymmetric integration with a range of time constants. Although the results largely support the present low frequency weighting curve, they also indicate that asymmetric integration provides better program loudness assessment than symmetric integration or high level gating.
Convention Paper 8341 (Purchase now)

P5-2 Evaluation of Live Meter Ballistics for Loudness ControlScott Norcross, Communications Research Centre - Ottawa, Ontario, Canada; Félix Poulin, CBC/Radio-Canada - Montreal, Quebec, Canada; Michel Lavoie, Communications Research Centre - Ottawa, Ontario, Canada
The broadcast community is transitioning from practices that revolved around audio peak normalization to one where the focus is on loudness consistency. Central to this effort is the loudness measurement algorithm described in ITU-R BS.1770. To assist in the mixing of audio that targets specific long-term loudness levels a need has been identified for some form of loudness-based live audio metering. The EBU has proposed meter specifications to indicate “momentary” and “short-term” loudness whose ballistics are defined, respectively, by a 400 ms and a 3000 ms integration window. In parallel with the EBU efforts, the CBC/Radio-Canada, in collaboration with the CRC, has been studying since 2008 various loudness meter ballistics that would be suitable in a production environment. This paper reports on a series of tests carried out by the CBC/Radio-Canada where various momentary meter ballistics wee evaluated it was found that an IIR-based meter ballistic with a 400 ms time-constant was preferred.
Convention Paper 8342 (Purchase now)

P5-3 Adaptive Dynamics EnhancementMartin Walsh, Edward Stein, Jean-Marc Jot, DTS, Inc. - Scotts Valley, CA, USA
Modern recordings are being mastered with more and more aggressive dynamic range compression in an attempt to generate content that is louder than previous releases. This can often lead to large discrepancies in perceived loudness between tracks that were mastered at different periods of recent history. A commonly proposed solution to this problem involves the use of loudness normalization. While such normalization techniques help to reduce discrepancies in loudness, they cannot resurrect dynamics that were removed due to extreme levels of dynamic range compression. This paper outlines a technique for restoring the dynamics of modern music by continuously monitoring transient signal behavior together with the associated dynamic range levels. When dynamic range compression is likely, transients are restored to levels that are more expected for the type of material being played.
Convention Paper 8343 (Purchase now)

P5-4 Describing the Transparency of Mixdowns: The Masked-to-Unmasked-RatioPhilipp Aichinger, Medical University of Vienna - Vienna, Austria University of Music and Performing Arts Graz, Graz, Austria; Alois Sontacchi, University of Music and Performing Arts Graz - Graz, Austria; Berit Schneider-Stickler, Medical University of Vienna - Austria
In this paper a model that predicts the transparency of mixdowns is proposed. The Masked-to-Unmasked-Ratio relates the original loudness of an instrument to its loudness in the mix. In order to assess this new measure a listening test is conducted. It is shown that instruments with a Masked-to-Unmasked-Ratio of 10% or smaller are critical in mixdowns because most of them cannot be identified adequately. The newly suggested model is to be used in automatic mixdown algorithms and as an evaluating measure in future development whenever masking scenarios are to be described.
Convention Paper 8344 (Purchase now)

P5-5 The "Digital Solution”: The Answer to a Lot of Challenges within New Production Routines at Today’s Broadcasting StationsStephan Peus, Georg Neumann GmbH - Berlin, Germany
The introduction of networked production systems allows a very actual, topical, and efficient workflow especially within broadcast and TV applications. As a result production is moving closer to editorial work. Sound editing such as voice-over, etc., has to be done more and more by editors who naturally don’t have that special knowledge as a sound engineer. Life recordings and interactive TV in future will call for further steps to simplify the production processes and to enhance reliability. We will explain practical examples of challenges from daily production routines, will give answers to solve the problems by using digital technology, and will show the effects on a more simple and reliable workflow.
Convention Paper 8345 (Purchase now)

P5-6 Automatic Mixing and Tracking of On-Pitch Football Action for Television BroadcastsRobert G. Oldfield, Benjamin G. Shirley, University of Salford - Salford, UK
For the television broadcast of football in Europe, the sound engineer will typically have an arrangement of 12 shotgun microphones around the pitch to pick up on-pitch sounds such as whistle blows, players talking, and ball kicks, etc. Typically, during a match, the sound engineer will increase and decrease the levels of these microphones manually in accordance with where the action is on the pitch at a given time to prevent the final mix being awash with crowd noise. As part of the EU funded project, FascinatE, we have developed an automatic mixing algorithm that intelligently seeks key events on the pitch and turns on the corresponding microphones, the algorithm picks out the key events and automatically tracks the action eliminating the need for manual tracking.
Convention Paper 8346 (Purchase now)

P5-7 High Quality “Radio” Broadcasting over the InternetDavid Errock, Wave Science Technology Ltd. - London, UK
Broadcasting audio over the internet has dramatically improved the experience for listeners, including removing the geographic boundaries of terrestrial transmission, allowing playback on portable devices and time-shifting content. Internet audio has primarily increased choice with traditional broadcasters now competing alongside “internet only” music stations. Internet distribution can also increase the audio quality, beyond that of terrestrial and satellite transmission channel constraints; unlike video streaming, which is of lower perceived quality than traditional transmission. With the sustainable data capacity of internet connections increasing, lossless audio can be streamed live to the consumer. This paper discusses the issues relating to these distribution techniques and the challenges that will be experienced by the broadcasters, the distribution network, receiver manufacturers, and listeners.
Convention Paper 8347 (Purchase now)

P6 - Audio Equipment


Friday, May 13, 16:30 — 18:00 (Room: Foyer)

P6-1 Study and Analysis of the Carrier Distortion Sources in PWM DCI-NPC ModulatorVicent M. Sala, Luis Romeral, UPC-Universitat Politecnica de Catalunya - Terrassa, BCN, Spain
This paper studies and analyzes an analog PWM Modulator for a Half-Bridge DCI-NPC Amplifier (Diode Clamped Inverter - Neutral Point Clamped) as one of the sources of distortion in the switching amplification chain. The four types of error or distortion sources are studied and analyzed: Carriers Offset Error (COE), Carriers Phase Error (CPE), Carriers Symmetry Error (CSE), and Carriers Amplitude Error (CAE). This paper concludes that the two major sources of error or distortion in PWM modulation process for DCI-NPC topology are the Amplitude (CAE) and Offset (COE) Errors, the latter being largest contributor to the total distortion.
Convention Paper 8348 (Purchase now)

P6-2 Experimental Verification of an Electrostatic Transducer with a Partitioned Back ElectrodeLibor Husník, Czech Technical University in Prague - Prague, Czech Republic
Electroacoustic transducers based on the condenser principle have usually a planar back electrode that is a one-piece entity. The previous work studied theoretically the possibility of making the back electrode partitioned. Such an arrangement can be used in a design of the so-called digital loudspeaker, in which the sizes of the partitioned electrode are in the ratio of the powers of 2, but this is only a special case. The aim of this work is to study performance of a system modeling the electrostatic transducer with the partitioned back electrode by way of measurement on an experimental sample. Various combinations of signals are applied on the partitioned electrode and the transducer response is measured.
Convention Paper 8349 (Purchase now)

P6-3 Capacitor “Sound” in Microphone Preamplifier DC Blocking and HPF Applications: Comparing Measurements to Listening TestsRobert-Eric Gaskell, McGill University - Montreal, Quebec, Canada
The sonic effect of capacitors in various aspects of audio electronics design has long been discussed and speculated upon. Recent publications have tested many of these theories through rigorous distortion measurements of a variety of capacitor types under several test conditions. One particularly interesting result is a measurable increase in 2nd harmonic distortion for electrolytic and PET type capacitors when a DC bias is applied. This paper repeats these measurements for a set of capacitors commonly used in +48V blocking applications and high pass filters in microphone preamplifier designs. These physical measurements are then compared to the result of double blind listening tests in order to examine the audibility of these capacitor distortions as well as explore their sonic effect on various program materials.
Convention Paper 8350 (Purchase now)

P6-4 1W 104dBA SNR Filterless Fully-Digital Class D Audio Amplifier with EMI Reduction TechniqueRossella Bassoli, Carlo Crippa, Federico Guanziroli; Germano Nicollini, ST-Ericsson - Agrate Brianza, Monza Brianza, Italy
A 1W filter-less power DAC featuring 104dBA SNR and EMI spreading is presented. Pre-distortion algorithms are used to reduce harmonic distortion inherent to the employed modulation process, and an oversampling noise shaper allows reducing modulator clock speed to facilitate hardware implementation while keeping high-fidelity quality. No analog circuits exist from I2S interface to speaker, leading to zero output offset and good efficiency even at medium/low power levels. 1.2V digital and 2.7V-5V output supplies are used. Active area is 0.94mm2 in a 0.13micron CMOS process. Total harmonic distortion at maximum level is about 0.2%.
Convention Paper 8351 (Purchase now)

P6-5 Ultra-Low Power Audio Architecture for Portable DevicesKangeun Lee, Changyong Son, Dohyung Kim, Sihwa Lee, Samsung Advanced Institute of Technology - Suwon, Korea
Current portable devices demand not only higher performance but also lower power consumption. For the reason, this paper describes a low power System-on-Chip (SoC) architecture that targets playback multimedia format. To significantly reduce power consumption of the SoC, the system exploits a DSP core to decode compressed audio. It is a key technique that a pre-buffer keeps compressed audio data. Therefore, the DSP can independently playback audio data, and other systems including CPU, and DRAM is able to be power off until all audio data remaining in the pre-buffer is exhausted by the DSP. For seamless operation, we designed a new kernel driver that controls the DSP and CPU, and it is embedded into Linux kernel sets of the Google’s Android 2.2. Energy efficiency is evaluated by using fourteen audio sequences encoded with mp3 of which format is 128kbps stereo. The experimental results show that the proposed system required only 25% power of the conventional DVFS algorithm and guaranteed Quality of Service (QoS) for mp3 playing.
Convention Paper 8352 (Purchase now)

P6-6 Design of a Passive DGRC Column Loudspeaker with Wave Front SynthesisXavier Meynial, Gilles Grégoire, Active Audio - Saint-Herblain, France
The DGRC (Digital and Geometric Radiation Control) principle allows one to assign a large number of loudspeakers of a line array to a limited number of electronic channels. It was introduced in 2006 and is now used in digitally steerable column loudspeakers. In this paper we propose a very simple and straightforward implementation of this principle in a passive column, where delays are approximated with all-pass passive circuits. As a result, the column is placed vertically (not tilted) and radiates a wave front that ensures high speech intelligibility and homogeneous SPL coverage. We present the design of this column, as well as experimental results. Finally, we discuss its advantages in terms of visual integration, acoustic performances, and cost effectiveness.
Convention Paper 8353 (Purchase now)

P6-7 Design and Realization of a Reference Class Loudspeaker Panel for Wave Field SynthesisStephan Mauer, Frank Melchior, IOSONO GmbH - Erfurt, Germany
This paper describes the requirements, the design, and the realization of a reference loudspeaker panel for Wave Field Synthesis (WFS). Beside the algorithm and the loudspeaker's acoustical performance the quality of Wave Field Synthesis is strongly dependent on the spatial aliasing frequency. Only below that frequency will the synthesized wave field be physically correct. The spatial aliasing frequency is related to the distance of adjacent speakers in the loudspeaker array. To raise the aliasing frequency to 2.8 kHz a loudspeaker panel was designed with a tweeter spacing of 6 cm. The transducers, electronics, and directivity were designed to obtain an excellent sound quality and SPL coverage. Simulations regarding the influence of speaker spacing and wave field artifacts have been made. Measurement results of the panel are given. The overall system design will be shown as an application example.
Convention Paper 8354 (Purchase now)

P6-8 Study and Analysis of Demodulation Filter Losses in DCI-NPC Multilevel Power AmplifiersVicent M. Sala, Luis Romeral, UPC-universitat Politecnica de Catalunya - Terrassa, BCN, Spain
This paper presents a less studied source of efficiency losses in Multilevel Diode-Clamped-Inverter or Neutral-Point-Converter (DCI-NPC) Power Switching Amplifiers. Filter inductors generally add another significant contribution to the total power loss in Power Switching Amplifiers systems. This contribution is generally comparable to that of the switching power stage and it is important to obtain a reasonable accurate estimate of the losses. In this paper the four possible sources of losses in the demodulation filter are studied and analyzed and are defined the expressions to calculate the value of the losses. Using these loss expressions, this paper analyzes the contribution of each of the sources. This work finishes up presenting the results of simulation and the conclusions.
Convention Paper 8355 (Purchase now)

P7 - Live and Interactive Sound


Saturday, May 14, 09:00 — 11:00 (Room 1)

Chair:
Michael Kelly

P7-1 User Driven, Local Model, Reclassification of Drum Loop Audio SlicesHenry Lindsay-Smith, Queen Mary University of London - London, UK; Skot McDonald, FXpansion Audio Ltd. - London, UK; Mark Sandler, Queen Mary University of London - London, UK
We present a method for significantly improving the results of drum loop slice classification. An onset detector is used to slice loops of percussion only audio. Low level features are extracted from the audio slices and the slices are classified into one of seven percussion classes by a previously trained PART decision table. This general classification algorithm shows only an adequate performance. The user is then allowed to correct incorrect classifications. Each corrected classification is combined with a subset of the original classifications and a nearest neighbor algorithm reclassifies the remaining slices according to the corrected local model. The resultant algorithm converges on a 100% correct solution, with nearly 40% fewer re-classifications than a non-assisted approach.
Convention Paper 8356 (Purchase now)

P7-2 Kick-Drum Signal Acquisition, Isolation and Reinforcement Optimization in Live SoundAdam J. Hill, Malcolm O. J. Hawksford, University of Essex - Colchester, Essex, UK; Adam P. Rosenthal, Gary Gand, Gand Concert Sound - Glenview, IL, USA
A critical requirement for popular music in live-sound applications is the achievement of a robust kick-drum sound presented to the audience and the drummer while simultaneously achieving a workable degree of acoustic isolation for other on-stage musicians. Routinely a transparent wall is placed in parallel to the kick-drum heads to attenuate sound from the drummer’s monitor loudspeakers, although this can cause sound quality impairment from comb-filter interference. Practical optimization techniques are explored, embracing microphone selection and placement (including multiple microphones in combination), isolation-wall location, drum-monitor electronic delay, and echo cancellation. A system analysis is presented augmented by real-world measurements and relevant simulations using a bespoke Finite-Difference Time-Domain (FDTD) algorithm.
Convention Paper 8357 (Purchase now)

P7-3 Development of a Virtual Performance Studio with Application of Virtual Acoustic Recording MethodsIain Iaird, Glasgow School of Art - Glasgow, Scotland, UK; Damian Murphy, University of York - Heslington, York, UK; Paul Chapman, Glasgow School of Art - Glasgow, Scotland, UK; Seb Jouan, Arup - Glasgow, Scotland, UK
A Virtual Performance Studio (VPS) is a space that allows a musician to practice in a virtual version of a real performance space in order to acclimatize to the acoustic feedback received on stage before physically performing there. Traditional auralization techniques allow this by convolving the direct sound from the instrument with the appropriate impulse response on stage. In order to capture only the direct sound from the instrument, a directional microphone is often used at small distances from the instrument. This can give rise to noticeable tonal distortion due to proximity effect and spatial sampling of the instrument’s directivity function. This work reports on the construction of a prototype VPS system and goes on to demonstrate how an auralization can be significantly affected by the placement of the microphone around the instrument, contributing to a reported “PA effect.” Informal listening tests have suggested that there is a general preference for auralizations that process multiple microphones placed around the instrument.
Convention Paper 8358 (Purchase now)

P7-4 Interactive Audio Realities: An Augmented / Mixed Reality Audio Game PrototypeNikos Moustakas, Andreas Floros, Nicolas Grigoriou, Ionian University - Corfu, Greece
Audio-games represent a game alternative based on audible feedback rather than on visual. They may benefit from parametric sound synthesis and advanced audio technologies (i.e., augmented reality audio), in order to effectively realize complex scenarios. In this paper a multiplayer game prototype is introduced that employs the concept of controlled mixed reality in order to augment the sound environment of each player. The prototype is realized as multiple user audiovisual installations, which are interconnected in order to communicate the status of the selected control parameters in real-time. The prototype reveals significant relevance to the-well known on-line multiplayer games, with its novelty originating from the fact that user interaction is realized in augmented reality audio environments.
Convention Paper 8359 (Purchase now)

P8 - Audio Equipment


Saturday, May 14, 09:00 — 12:30 (Room 4)

Chair:
John Dawson

P8-1 Signal Level and Frequency Dependant Losses Inside Audio Signal Transformers and How to Prevent ThoseMenno van der Veen, ir. bureau Vanderveen - Zwolle, The Netherlands
In an earlier work (Convention Paper 7125) a model was presented that explains that low voltage level audio signals are extra weakened when they are fed through a transformer. This extra weakening is caused by the signal level and frequency dependent inductance of the transformer. Combining this extra weakening with the threshold of hearing curves, showed that noticeable loss of micro details occurs in the frequency band from 20 Hz to 1 kHz. This paper expands the previous work with measurements on several valve amplifiers, refines the model, and makes it applicable to macro signal levels close to saturation of the transformer. Methods are also given to minimize this extra weakening in transformers.
Convention Paper 8360 (Purchase now)

P8-2 Diaphonic Pump: A Sound-Activated Alternating to Static Pressure ConverterStephen D. Ambrose, Robert Schulein, Asius Technologies LLC - Longmont, CO, USA; Samuel Gido, Asius Technologies LLC - Longmont, CO, USA, University of Massachusetts, Amherst, MA, USA
This paper discusses the operating principles and basic construction of a diaphonic pump, which is a newly invented device for harvesting the energy inherent in sound waves and using it to pump air, thereby pressurizing a vessel. Although this device is of general utility, the embodiment discussed in this paper is used to harvest sound energy from the speaker (balanced armature transducer) of a personal listening device (headset or hearing aid), and use this as a power source to inflate a bubble in the listener’s ear, thereby creating an acoustic seal. The diaphonic pump utilizes a natural asymmetry in the flow pattern when fluid is alternatingly pushed and pulled, back and forth through a small orifice known as a “synthetic jet.” Sound waves provide the alternating flow pattern across the synthetic jet orifice. Prototype diaphonic pumps were built, which attach to a back volume of a balanced armature transducer and are small enough that the whole assembly, transducer, and pump, can fit in a human ear canal.
Convention Paper 8361 (Purchase now)

P8-3 Scanning the Magnetic Field of Electro-Dynamical TransducersWolfgang Klippel, University of Technology - Dresden Germany, Klippel GmbH, Dresden, Germany
The magnetic flux density in the magnetic gap and the geometry of the moving coil determine the force factor Bl, which is an important parameter of the electro-dynamical transducer. The paper presents a new measurement technique for scanning the flux density B(z, f) on a cylindrical surface within and outside the magnetic gap using a Hall sensor and robotics changing the position of the sensor versus vertical position z and angle f. The results derived from the scanning process reveal the real B field in the gap considering the fringe field and irregularities in the magnetization, which may initiate a rocking mode and rubbing of the voice coil at higher amplitudes. Using the geometry of the coil the static force factor Bl(x, i=0) can be calculated as a function of voice coil displacement x and compared with the dynamic force factor B(x,i) measured by a dynamic system identification techniques. Discrepancies between dynamic and static force factor characteristics are discussed and conclusions for loudspeaker design and manufacturing are derived.
Convention Paper 8362 (Purchase now)

P8-4 Comparison of Anemometric Probe and Tetrahedral Microphones for Sound Intensity MeasurementsGiulio Cengarle, Toni Mateos, Fundació Barcelona Media - Barcelona, Spain
The measurement of sound intensity requires the acquisition of sound pressure and acoustic velocity in a coincident position. Various transducer topologies can be used to measure the acoustic velocity directly or indirectly. In this paper three transducers are compared: a pressure-velocity anemometric probe and two tetrahedral B-Format microphones from different manufacturers. The comparison has been carried out in different fields, ranging from anechoic to diffuse, reverberant field conditions. The analysis and comparison is based on intensimetric quantities such as the radiation index and the sound intensity vector. Strengths and limitations of the various approaches are reported, to suggest the preferred applications for each transducer.
Convention Paper 8363 (Purchase now)

P8-5 Prediction of Perceived Width of Stereo Microphone SetupsHans Riekehof-Böhmer, HAW-Hamburg - Hamburg, Germany; Helmut Wittek, Schoeps Mikrofone - Karlsruhe, Germany
The diffuse-field correlation of the two signals generated by a stereophonic microphone setup has an effect on the perception of spatial width. A correlation meter is often used to measure the correlation coefficient. However, due to the frequency dependence of the correlation function, the correlation coefficient is not an appropriate value for predicting the perceived width when it comes to time-delay stereophony. By using the newly defined “Diffuse-Field-Image-Predictor” (DFI-Predictor) presented in this paper an attempt is made to reliably predict perceived width. Listening tests show that the DFI-Predictor is fairly suitable for this task. The aim of the study is to compare the spatial properties of different stereophonic microphone techniques by one calculated value.
Convention Paper 8364 (Purchase now)

P8-6 Synthesis of Polar Patterns as a Function of Frequency with a Twin Microphone: Audio Examples and Applications within the Creative Process of Music MixingMatthias Kock, Erich-Thienhaus-Institute - Detmold, Germany; Markus Kock, Leibniz Universität Hannover - Hannover, Germany; Malte Kob, Erich-Thienhaus-Institute - Detmold, Germany; Rainer Maillard, Emil-Berliner Studios - Berlin, Germany
The directivity of a twin microphone can be chosen by variable weighting of the two output signals. In addition, the polar pattern can be adjusted as a function of frequency when controlled with a VST Plug-in in a modern DAW environment. A number of recordings were performed in rooms with variable size and quality. Presets with beneficial frequency-dependent directivities are compared to settings with constant directivity. It is discussed to what extend recordings can be further improved using the plug-in.
Convention Paper 8365 (Purchase now)

P8-7 Digital Microphones—What’s it All About?John Willett, Circle Sound Services - Oxfordshire, UK
It’s now ten years since the first AES42 specification was published (AES42-2001) and the first AES42-compliant digital microphone came to the market. So this seems an opportune moment to look at AES42 digital microphones, their history, what they offer, the current market situation, and what the future may hold.
Convention Paper 8366 (Purchase now)

P9 - Perception and Evaluation


Saturday, May 14, 09:00 — 10:30 (Room: Foyer)

P9-1 The Effect of Loudness Overflow on Equal-Loudness-Level ContoursAndrew J. R. Simpson, Joshua D. Reiss, Queen Mary University of London - London, UK
This paper presents a formal derivation of the Loudness Overflow Effect (LOE), which describes the impact of nonlinear distortion on loudness. Computational analysis is then performed, comprised of two experiments involving two compressive static nonlinearities and using two well-known time-varying loudness models. The results characterize the nonlinearities in terms of LOE as a function of frequency and of listening level in the case of 250-ms pure-tone stimuli, and in terms of the traditional equal-loudness-level contours. The analysis is then extended to synthesized wind instruments for one of the nonlinearities. The effect of the nonlinearity on loudness as a function of musical note fundamental frequency and listening level is described for various synthesized instruments.
Convention Paper 8367 (Purchase now)

P9-2 Evaluating the Use of Audio Smartphone Apps for Higher EducationAnne Nortcliffe, Andrew Middleton, Ben Woodcock, Sheffield Hallam University - Sheffield, UK
Digital audio technology has garnered interest in Education recently, being deployed by early adopter academics to provide audio feedback. Students have also used it, gathering audio notes on their personal devices to enhance their learning. However, the sharing and distributing of the recordings is time-consuming and requires separate technology. Smartphones with audio apps are able to support recording and distribution/sharing of learning conversations more effectively because of their additional customizable and integrated functionality. This is attractive to Education now that it is clear that smartphones are becoming ubiquitous on campus. This paper describes an evaluation of audio apps for recording learning conversations by an academic and students and their experience in using smartphone audio apps to date.
Convention Paper 8368 (Purchase now)

P9-3 A Study of Human Perception of Temporal and Spectral Distortion Caused by Subwoofer ArraysElena Shabalina, RWTH Aachen University - Aachen, Germany; Janko Ramuscak, d&b audiotechnik GmbH - Backnang, Germany; Michael Vorländer, RWTH Aachen University - Aachen, Germany
The key task for a sound reinforcement system is to provide an even sound pressure level distribution over the whole listening area with possibly the same frequency response; and reduce radiation in wrong directions. For that a system should show a certain directivity, which for low frequencies can be achieved only by using multiple sound sources, for example, placed in a row in front of the stage. This technique can help to avoid strong interference and corresponding space sound pressure level variations of the conventional left/right setup of subwoofers. On the other hand, multiple sources cause changes of the impulse and frequency response of an array. Listening tests showed that these changes are audible for experienced listeners.
Convention Paper 8369 (Purchase now)

P9-4 Evaluation of the Psychoacoustic Perception of Geometric Acoustic Modeling-Based AuralizationAglaia Foteinou, Damian T. Murphy, University of York - Heslington, York, UK
The subjective evaluation of the auralization of a simulated acoustic, with a view to establishing the success or otherwise of the results obtained, is usually best achieved using listening tests comparing the virtual environment with the actual measured space. As existing modeling methods still need to be improved, it is of critical importance to focus on the human perception of acoustic of the given space, rather than optimizing room acoustic parameters based only on objective measures. This paper uses a much simplified representation of a space with the resulting computer model giving the capability to control all of the examined acoustic or simulation parameters independently. A 3-D shoebox shape room is created and a variety of factors are changed every time in order to investigate their relevance and influence on human perception. These results are obtained from listening tests, and conclusions for the psychoacoustic perception of such a space are given.
Convention Paper 8370 (Purchase now)

P9-5 A Comparative Perceptual Evaluation of the Timbral Variations in Choral Location Recordings Created by Four Common Stereo Microphone TechniquesDuncan Williams, University of Oxford (Wolfson College) - Oxford, UK
Choral recordings created on location were evaluated perceptually to determine the nature of the variations in timbre that might be elicited by the use of different stereo microphone techniques. Four stereo recordings were made simultaneously with coincident, near coincident, and spaced stereo microphone techniques. Listeners were invited to describe any perceived changes through a verbal elicitation experiment, informing an adjective “pool” of possible attributes. These attributes were reduced in number to six by verbal protocol analysis. The six remaining attributes were then scaled in a second listening experiment. Mean and standard deviation values in the results suggested that there was variation in three timbral attributes. This illustrated that the manipulation of timbral attributes by microphone technique, combined with perceptual analysis, is possible.
Convention Paper 8371 (Purchase now)

P9-6 Anchor Signals Validation for Two Dimensions of a Four-Dimensional Perceptive SpaceYves Zango, Orange Labs Lannion Tech/Opera - Lannion Cedex, France, INSERM U642, Rennes France, Université de Rennes, Rennes France; Régine Le Bouquin-Jeannès, INSERM U642 - Rennes France, Université de Rennes, Rennes France; Nathalie Costet, INSERM U642 - Rennes France, Université de Rennes, Rennes France; Catherine Quinquis, Orange Labs Lannion Tech/Opera - Lannion Cedex, France
The subjective assessment of speech and sound codecs requires anchor signals to ensure its reliability. The reference system currently used is Modulated Noise Reference Unit (MNRU), which simulates only quantization noise. Now, the new generations of codecs present other impairments. In this study we consider speech quality as a multidimensional phenomenon and use dimensional reduction techniques to project codecs' impairments in a four-dimensional space, each axis of the perceptive space corresponding to one of them. A verbalization test allowed characterizing two of these dimensions by the following attributes: “muffle” and “background noise.” Anchor signals were designed for these two dimensions, and a statistical analysis allowed validating the accuracy of at least one of these signals.
Convention Paper 8372 (Purchase now)

P9-7 Auditory Distance Perception: Criteria and Listening RoomJean-Christophe Messonnier, Conservatoire de Paris CNSMDP - Paris, France; Alban Moraud, Altia - Paris, France
This paper is the result of a series of listening experiments carried out to investigate the correlation between auditory distance and two criteria: the ratio of direct to reverberant sound energy and the clarity C80. In the first section of this paper we will determine which of the two criteria is more efficient. The second section compares the values of these criteria when the same signal is played on a well damped control room loudspeaker system and when it is played on a domestic stereophonic loudspeaker system. A second series of listening experiments shows how the auditory distance is perceived in both cases.
Convention Paper 8373 (Purchase now)

P9-8 Subjective Comparison between Stereo and Binaural Processing from B-Format Ambisonic Raw Audio MaterialFábio W. Sousa, University of York - York, North Yorkshire, UK
Using audio recorded in Ambisonic B-format from a sound field microphone and processed through both stereo and binaural tools, a subjective comparison is made. Hearing tests were performed taking into account personal experience and preference, as well as some spatial attributes concepts defined in previous works. Aiming to evaluate the real effectiveness of binaural processing, this paper considers the possibility of distributing contemporary music, originally developed for Ambisonic reproduction, through either conventional stereo or a method of high fidelity spatial processing directed specifically to reproduction through headphone systems, based on binaural technology. The sound images represented in both binaural and stereo processing are examined. Spatial attributes like wideness, depth, naturalness, and presence are evaluated.
Convention Paper 8374 (Purchase now)

P10 - Audio Content Management


Saturday, May 14, 11:00 — 13:00 (Room 1)

Chair:
Jamie A. S. Angus

P10-1 A Comprehensive and Modular Framework for Audio Content Extraction, Aimed at Research, Pedagogy, and Digital Library ManagementOlivier Lartillot, University of Jyväskylä - Jyväskylä, Finland
We present a framework for audio analysis and the extraction of low-level features, mid-level structures, and high-level concepts, altogether studied as a fully interwoven complex system. Composite operations are constructed via an intuitive programming language on top of Matlab. Datasets of any size can be processed thanks to implicit memory management mechanisms. The data structure enables a tight articulation between signal and symbolic layers in a unified framework. The resulting technology can be used as a pedagogical tool for the understanding of audio, speech, and musical processes and concepts, and for content-based discovery of digital libraries. Other applications includes intelligent browsing and structuring of digital library, information retrieval, and the design of content-based audio interfaces.
Convention Paper 8375 (Purchase now)

P10-2 Selected Playback Problems of Historical Grooved MediaNadja Wallaszkovits, Franz Lechleitner, Phonogrammarchiv Austrian Academy of Sciences - Vienna, Austria; Heinrich Pichler, Audio Consultant - Vienna, Austria
The paper discusses some selected playback problems of the replay and high quality archival transfer of historical grooved media, like cylinders, instantaneous discs and early coarse groove records. The topics outline the problems of noise reduction and the compensation of the horizontal tracking angle by means of stereo playback and modification of the sum and differential signals. A comparison between existing noise reduction methods and analog as well as digital phase and group delay compensation methods is given and discussed. Finally possible compensation methods for the change in noise spectrum caused by the groove velocity decrease at inner diameters with early discs are outlined. The authors propose a radius equalization in the digital domain by using a digital high pass filter without group delay distortion, using diameter dependent change of cut-off frequency.
Convention Paper 8376 (Purchase now)

P10-3 Automatic Recognition of Events in Audio Data Using Supercomputer ClusterKuba Lopatka, Andrzej Czyzewski, Henryk Krawczyk, Gdansk University of Technology - Gdansk, Poland
Dangerous events’ automatic recognition by audio analysis employing parallel processing on a supercomputer cluster is described in the paper. Sound files recorded by microphones operating in a security surveillance system are processed by a sound event detection and classification algorithm. Because of the large amount of data, parallel computation is employed to speed up the analysis. The sound file recorded by the surveillance system is divided into chunks and processed by separate threads or processes. Several strategies for such parallel computation are introduced and discussed. Results obtained in tests using a supercomputer cluster are presented.
Convention Paper 8377 (Purchase now)

P10-4 Using Support Vector Machines for Automatic Mood Tracking In Audio MusicRenato Panda, Rui Pedro Paiva, University of Coimbra - Coimbra, Portugal
In this paper we propose a solution for automatic mood tracking in audio music, based on supervised learning and classification. To this end, various music clips with a duration of 25 seconds, previously annotated with arousal and valence (AV) values, were used to train several models. These models were used to predict quadrants of the Thayer’s taxonomy and AV values, of small segments from full songs, revealing the mood changes over time. The system accuracy was measured by calculating the matching ratio between predicted results and full song annotations performed by volunteers. Different combinations of audio features, frameworks, and other parameters were tested, resulting in an accuracy of 56.3% and showing there is still much room for improvement.
Convention Paper 8378 (Purchase now)

P11 - Room Acoustics


Saturday, May 14, 14:00 — 17:30 (Room 1)

Chair:
Diemer de Vries

P11-1 DTS Multichannel Audio Playback System: Characterization and CorrectionZoran Fejzo, DTS, Inc. - Calabasas, CA, USA; James Johnston, DTS, Inc. - Kirkland, WA, USA
Audio playback system correction methods are now commonplace in audio-video receivers. One goal of these systems is to correct deviation of loudspeaker/room frequency response from some desired target curve. Unfortunately this correction may be inappropriate outside of a small area around the microphone location, and averaged measurements may provide unwanted timbre shifts. Some room correction algorithms capture the room responses at multiple locations and combine them to obtain a representative response that is used for frequency correction. We will present a loudspeaker / room correction system that attempts to achieve perceptually appropriate frequency correction in a wide listening area by using a closely spaced non-coincident multi-microphone array placed in a single location in the room. By use of special probe signals, this is achieved within a short measurement period.
Convention Paper 8379 (Purchase now)

P11-2 Evaluating the Auralization of Performance Spaces and Its Effect on Singing PerformanceJudith Brereton, Damian T. Murphy, David M. Howard, University of York - Heslington, York, UK
Musicians alter their performance according to the acoustic environment in which they perform, but as yet a thorough parametric investigation of the effect of room acoustics on musical performance has not yet been achieved. A sufficiently “realistic” synthesized Room Impulse Response (RIR) will facilitate such a study, since this will allow the investigator greater control and knowledge of the room acoustic parameters involved. This paper reports the results of an experiment to evaluate a virtual acoustic space through the performance, interview, and audio analysis of the performance of a solo singer. Simulations of the same performance space using synthesized RIRs and measured RIRs were compared. In general, singers who took part in the trial could distinguish between the two simulations and rated the measured RIR simulation more highly in terms of warmth and reverberance.
Convention Paper 8380 (Purchase now)

P11-3 Enhancing the Configuration and Design of Sound Systems through SimulationFrederick Otten, Richard Foss, Rhodes University - Grahamstown, South Africa
Audio Engineers are required to design and deploy large multichannel sound systems that meet a set of requirements and use networking technologies such as Firewire and Ethernet. Bandwidth utilization and latency need to be considered. Network Simulation can be used to accurately model a network and return such information. This paper discusses a software system that has been developed to create a simulation of a network using the AES-X170 protocol for command and control. This system shows information about bandwidth and latency and is able to detect problems with parameter relationships. It also provides the ability to perform offline editing. These features significantly enhance the audio engineer’s ability to effectively design, configure, and evaluate their sound systems.
Convention Paper 8381 (Purchase now)

P11-4 What’s Wrong with Scattering Theory?Ian M. Dash, Fergus R. Fricke, University of Sydney - Sydney, NSW, Australia
The theory of long wave scattering from the side of a cylinder originated with Rayleigh and was extended to a general solution by Morse. Both solutions are based on an angular harmonic series expansion. This model is conceptually flawed. A number of physical paradoxes inherent in the model are outlined and discussed.
Convention Paper 8382 (Purchase now)

P11-5 New Proposals for the Calibration of Sound in Cinema RoomsPhilip Newell, Acoustics Consultant - Moaña, Spain; Keith Holland, ISVR, University of Southampton - Southampton, UK; Julius Newell, Electroacoustics Engineer - Lisbon, Portugal; Branko Neskov, Loudness Films - Lisbon, Portugal
The current practices for calibrating cinema rooms date back to the early 1970s. Much has been learned since then about the perception of sound, and measurement techniques have advanced greatly. Evidence has been growing that the present degree of room-to-room compatibility leaves much to be desired, and complaints about loudness and intelligibility problems persist. This paper looks at reassessing the whole process of the loudspeaker and room calibration from a modern perspective.
Convention Paper 8383 (Purchase now)

P11-6 Some Preliminary Comparisons between the Diffusion Equation Model and Room-Acoustic Rendering Equation in Complex ScenariosJuan M. Navarro, San Antonio’s Catholic University of Murcia - Guadalupe, Spain; Jose Escolano, University of Jaén - Linares, Spain; Jose J. López, Universidad Politecnica de Valencia - Valencia, Spain
Recently, a model named acoustic radiative transfer equation has been proposed as a general theory to expand geometrical room acoustic modeling algorithms. This room acoustic modeling technique establishes the basis of two recently proposed algorithms, the acoustic diffusion equation model and the room acoustic rendering equation. This paper presents some comparisons of room-acoustic parameters in-situ measurements with prediction values from both methods in a real complex shape room in order to clarify advantages and limitations of both methods. Moreover, the memory requirements and computation time have been evaluated.
Convention Paper 8384 (Purchase now)

P11-7 Spatial Room Impulse Responses with a Hybrid Modeling MethodAlex Southern, Samuel Siltanen, Lauri Savioja, Aalto University - Aalto, Finland
The synthesis of an arbitrary enclosure room impulse response (RIR) may be performed using acoustic modeling. A number of acoustic modeling methods have been proposed previously each with their own advantages and limitations. This paper is concerned with mixing the RIRs from different modeling methods to synthesize a hybrid RIR. Low frequencies are modeled using the finite difference time domain method (FDTD), high frequencies are treated with geometric methods. A practical implementation for forming a hybrid RIR is discussed and further demonstrated in the context of a 2nd order B-Format spatial encode of the modeled sound field. The paper discusses the considerations and limitations of forming such hybrid RIRs using wave-based and geometric-based methods.
Convention Paper 8385 (Purchase now)

P12 - Binaural Sound


Saturday, May 14, 14:00 — 17:30 (Room 4)

Chair:
Bozena Kostek

P12-1 Comparison of Speech Intelligibility in Artificial Head and Jecklin Disc RecordingsRoger Johnsson, Arne Nykänen, Luleå University of Technology - Luleå, Sweden
Binaural recordings are often done using artificial heads but can also be done with a Jecklin disc. In this study an experiment was designed that allowed evaluation of noise and reverberation suppression based on speech intelligibility measurements. Recordings of a voice and disturbing noise were done in a reverberant environment using one artificial head and four Jecklin discs of various sizes. A listening experiment using headphones was conducted to determine the speech intelligibility in the recordings and in a real life situation. It was found that there was no significant difference in the speech intelligibility between the artificial head and Jecklin disc with a diameter of 36 cm.
Convention Paper 8386 (Purchase now)

P12-2 A Comparison of Speech Intelligibility for In-Ear and Artificial Head RecordingsArne Nykänen, Roger Johnsson, Luleå University of Technology - Luleå, Sweden
Good binaural reproductions should allow the listener to suppress noise and reverberation as when listening in real life. An experiment was designed where room properties and reproduction techniques were varied in a way that allowed evaluation of noise and reverberation suppression based on speech intelligibility measurements. Artificial head recordings were compared to in-ear recordings and real life listening. Artificial head recordings were found to be equivalent to real life listening. The speech intelligibility for in-ear recordings surpassed real life listening. A possible explanation may be inaccurate equalization. The equalization is critical for correct reproduction of binaural cues. The procedure used is convenient for validation of the performance of recording and reproduction equipment intended for sound quality studies.
Convention Paper 8387 (Purchase now)

P12-3 Perceptually Robust Headphone Equalization for Binaural ReproductionBruno Masiero, Janina Fels, RWTH Aachen University - Aachen, Germany
Headphones must always be adequately equalized when used for reproducing binaural signals if they are to deliver high perceptual plausibility. However, the transfer function between headphones and ear drums (HpTF) varies quite heavily with the headphone fitting for high frequencies, thus even small displacements of the headphone after equalization will lead to irregularities in the resulting frequency response. Keeping in mind that irregularities in the form of peaks are more disturbing than equivalent valleys, a new method for designing headphone equalization filters is proposed where not the average but an upper variance limit of many measured HpTFs is inverted. Such a filter yields perceptually robust equalization since the equalized frequency response will, with high chance, differ from the ideal response only by the presence of valleys in the high frequency range.
Convention Paper 8388 (Purchase now)

P12-4 Prediction of Perceived Elevation Using Multiple Pseudo-Binaural MicrophonesTommy Ashby, Russell Mason, Tim Brookes, University of Surrey - Guildford, Surrey, UK
Computational auditory models that predict the perceived location of sound sources in terms of azimuth are already available, yet little has been done to predict perceived elevation. Interaural time and level differences, the primary cues in horizontal localization, do not resolve source elevation, resulting in the “Cone of Confusion.” In natural listening, listeners can make head movements to resolve such confusion. To mimic the dynamic cues provided by head movements, a multiple microphone sphere was created, and a hearing model was developed to predict source elevation from the signals captured by the sphere. The prototype sphere and hearing model proved effective in both horizontal and vertical localization. The next stage of this research will be to rigorously test a more physiologically accurate capture device.
Convention Paper 8389 (Purchase now)

P12-5 BRTF (Body Related Transfer Function) and Whole-Body Vibration Reproduction SystemsM. Ercan Altinsoy, Sebastian Merchel, Dresden University of Technology - Dresden Germany
If binaural recorded signals are played back via headphones, the transfer characteristic of the reproduction system has to be compensated for. Unfortunately, the transfer characteristic depends not only on the transducer itself, but also on mounting conditions and individual properties of the respective ear. This is similar with reproduction systems for whole-body vibrations. The transfer characteristic depends to a great extent on the individual body properties, e.g., weight or body mass index. In this study body related transfer functions of 60 subjects are measured using an electrodynamic excitation system. In addition anthropometric data of the subjects are collected. This paper reviews the existing whole-body vibration reproduction systems and discusses the importance of the individual transfer functions for whole-body vibration reproduction.
Convention Paper 8390 (Purchase now)

P12-6 HRTF-Enabled Microphone Array for Binaural SynthesisMalcolm O. J. Hawksford, University of Essex - Colchester, Essex, UK
A synthesis technique incorporating a circular phased-array microphone is described where the horizontal polar response is matched to an arbitrary set of head-related transfer functions (HRTFs). The array can emulate the function of an artificial listener but without the need to embed physical anatomical features. Design techniques are described based upon polar response equalization computed over a discrete frequency space that together with dynamic coefficient processing enables spatial image manipulation and bespoke multi-listener environments with individual head tracking. A method of 2-D spatial filtering is described to scale the number of microphone signals. Applications include binaural recording optimally matched to an arbitrary number of listeners, distributed gaming, teleconferencing, multi-user interactive virtual reality, and remote surveillance.
Convention Paper 8391 (Purchase now)

P12-7 Interpolation and Range Extrapolation of Head-Related Transfer Functions Using Virtual Local Wave Field SynthesisSascha Spors, Hagen Wierstorf, Jens Ahrens, Deutsche Telekom Laboratories, Technische Universität Berlin - Berlin, Germany
Virtual environments that are based on binaural sound reproduction require datasets of head-related transfer functions (HRTFs). Ideally, these HRTFs are available for every possible position of a virtual sound source. However, in order to reduce measurement efforts, such datasets are typically only available for various source directions but only for one or very few distances. This paper presents a method for extrapolation of measured HRTF datasets from the source distance used in the measurements to other source distances. The method applies the concept of local Wave Field Synthesis to compute extrapolated HRTFs for almost arbitrary source positions with high accuracy. The method is computationally efficient and numerically stable.
Convention Paper 8392 (Purchase now)

P13 - Production and Broadcast


Saturday, May 14, 16:30 — 18:00 (Room: Foyer)

P13-1 A Comparison of Kanun Recording Techniques as They Relate to Turkish Makam Music PerceptionCan Karadogan, Istanbul Technical University - Istanbul, Turkey
This paper presents a quality comparison of microphone techniques applied on the kanun, a prominent traditional instrument of Turkish Makam music. Disregarding the effects of pre-amplifier color, A/D converter, compression, equalization, mixing, and mastering, only the studio recording step of music production is taken into focus. Microphone techniques were applied with varying placements and microphone types, and doing so, original Turkish Makam music etudes were recorded. Using short excerpts of these etudes, a survey comparing microphone techniques and placements as well as microphone types was prepared. Subjects were chosen from kanun players, sound engineers, and non-musicians who showed different perspectives, preferences, and descriptions to the sound samples of various microphone techniques.
Convention Paper 8393 (Purchase now)

P13-2 Objective Measurement of Produced Music Quality Using Inter-Band Dynamic Relationship AnalysisSteven Fenton, University of Huddersfield - Huddersfield, UK; Bruno Fazenda, University of Salford - Salford, UK; Jonathan Wakefield, University of Huddersfield - Huddersfield, UK
This paper describes and evaluates an objective measurement that grades the quality of a complex musical signal. The authors have previously identified a potential correlation between inter-band dynamics and the subjective quality of produced music excerpts. This paper describes the previously presented Inter-Band Relationship (IBR) descriptor and extends this work by testing with real-world music excerpts and a greater number of listening subjects. A high degree of correlation is observed between the Mean Subject Scores (MSS) and the objective IBR descriptor suggesting it could be used as an additional model output variable (MOV) to describe produced music quality. The method lends itself to real-time implementation and therefore can be exploited within mixing, mastering, and monitoring tools.
Convention Paper 8394 (Purchase now)

P13-3 Evaluation of a New Algorithm for Automatic Hum Detection in Audio RecordingsMatthias Brandt, Jade University of Applied Sciences - Oldenburg, Germany; Thorsten Schmidt, Cube-Tec International - Bremen, Germany; Joerg Bitzer, Jade University of Applied Sciences - Oldenburg, Germany
In this paper an evaluation of a recently published hum detection algorithm for audio signals is presented. To determine the performance of the method, large amounts of artificially generated and real-world audio data, containing a variety of music and speech recordings, are processed by the algorithm. By comparing the detection results with manually determined ground truth data, several error measures are computed: hit and false alarm rates, frequency deviation of the hum frequency estimation, offset of detected start and stop times, and the accuracy of the SNR estimation.
Convention Paper 8395 (Purchase now)

P13-4 Interactive Mixing Using Wii ControllerRod Selfridge, Joshua Reiss, Queen Mary University of London - London, UK
This paper describes the design, construction, and analysis of an interactive gesture-controlled audio mixing system by the means of a wireless video game controller. The concept is based on the idea that the mixing engineer can step away from the mixing desk and become part of the performance of the piece of audio. The system allows full, live control of gains, stereo panning, equalization, dynamic range compression, and a variety of other effects for multichannel audio. The system and its implementation are described in detail. Subjective evaluation and listening tests were performed to assess usability and performance of the system, and the test procedure and results are reported.
Convention Paper 8396 (Purchase now)

P13-5 The Quintessence of a Waveform: Focus and Context for Audio Track DisplaysJörn Loviscach, Fachhochschule Bielefeld (University of Applied Sciences) - Bielefeld, Germany
Oscilloscope-style waveform plots offer great insight into the properties of the audio signal. However, their use is impeded by the huge spread of timescales extending from fractions of a millisecond to several hours. Hence, waveform plots often require zooming in and out. This paper introduces a graphical representation through a synthesized quintessential waveform that looks shows the spectrum of the traditional waveform plot but does so at a much larger timescale. The quintessential waveform can reveal details about single periods at zoom levels where a regular waveform plot only indicates the signal's envelope. Compression renders the enormous ranges of frequencies and amplitudes more legible.
Convention Paper 8397 (Purchase now)

P13-6 Spatial Audio Processing for Interactive TV ServicesJohann-Markus Batke, Jens Spille, Holger Kropp, Stefan Abeling, Technicolor, Research, and Innovation - Hannover Germany; Ben Shirley, Rob G. Oldfield, University of Salford - Salford, UK
FascinatE is a European funded project that aims at developing a system to allow end users to interactively navigate around a video panorama showing a live event, with the accompanying audio automatically changing to match the selected view. The audiovisual content will be adapted to the users particular kind of device, covering anything from a mobile handset equipped with headphones to an imersive panoramic display connected with large loudspeaker setup. We describe how to handle audio content in the FascinatE context, covering simple stereo through to spatial sound fields. This will be performed by a mixture of Higher Order Ambisonics and Wave Field Synthesis. Our paper focuses on the greatest challenges for both techniques when capturing, transmitting, and rendering the audio scene.
Convention Paper 8398 (Purchase now)

P13-7 Wireless High Definition Multichannel Streaming Audio Network Technology Based on the IEEE 802.11 StandardsSeppo Nikkila, Tom Lindeman, Valentin Manea, ANT – Advanced Network Technologies Oy - Helsinki, Finland
A novel approach for the wireless distribution of uncompressed real-time multichannel streaming audio is presented. The technology is based on the IEEE 802.11 Point Coordination Function, Contention Free Medium Access Control with size-optimized multicast frames. The implementation supports eight independent audio streams with simultaneous 24-bit audio samples at the rate of 192 kHz. Frame length alignment algorithm is developed for smooth, low jitter flow. An audio specific Forward Error Correction scheme and a low system latency inter-channel synchronization method are described. The clock drift is solved by a sample stuffing/stripping algorithm. Implemented hardware and software structures are presented and the technology is compared with other wireless audio networking concepts. Emerging multichannel content formats are briefly reviewed.
Convention Paper 8399 (Purchase now)

P13-8 Gestures to Operate DAW SoftwareWincent Balin, Universität Oldenburg - Oldenburg, Germany; Jörn Loviscach, Fachhochschule Bielefeld (University of Applied Sciences) - Bielefeld, Germany
There is a noticeable absence of gestures—be they mouse-based or (multi-)touch-based—in mainstream digital audio workstation (DAW) software. As an example for such a gesture consider a clockwise O drawn with the fi nger to increase a value of a parameter. The increasing availability of devices such as smartphones, tablet computers, and touchscreen displays raises the question in how far audio software can benefi t from gestures. We describe design strategies to create a consistent set of gesture commands. The main part of this paper reports on a user survey on mappings between 22 DAW functions and 30 single-point as well as multi-point gestures. We discuss the findings and point out consequences for user-interface design.
Convention Paper 8456 (Purchase now)

P14 - Multichannel/Spatial, Part 2


Sunday, May 15, 09:00 — 12:30 (Room 1)

Chair:
Russell Mason

P14-1 Spatial Analysis of Room Impulse Responses Captured with a 32-Capsule Microphone ArrayAngelo Farina, Alberto Amendola, Andrea Capra, Christian Varani, University of Parma - Parma, Italy
The authors developed a new measurement system, which captures 32-channel impulse responses by means of a spherical microphone array and a matrix of FIR filters, capable of proving frequency-independent directivity patterns. This allows for spatial analysis with resolution much higher than what was possible with obsolete sum-and-delay beamforming. The software developed for this application creates a false-color video of the spatial distribution of energy, changing with running time along the impulse response duration. A virtual microphone probe allows extraction of the sound coming from any specific direction. The method was successfully employed in three concert halls, providing guidance for correcting some acoustical problems (echo, focusing) and for placing sound reinforcement loudspeakers in optimal positions.
Convention Paper 8400 (Purchase now)

P14-2 Control of the Beamwidth of a Beamformer with a Fixed Array ConfigurationWan-Ho Cho, Chuo University - Tokyo, Japan; Marinus M. Boone, Delft University of Technology - Delft, The Netherlands; Jeong-Guon Ih, Korea Advanced Institute of Science and Technology (KAIST) - Daejeon, Korea; Takeshi Toi, Chuo University - Tokyo, Japan
The directional characteristic of the optimal beamformer of a transducer array depends not only on its hardware configuration but also on the stability factor. This parameter can be used to control the directivity of the array. In this paper a method, which is based on the proper selection strategy of the stability factor, is suggested to control the directional characteristics of the optimal beamformer without changing the array configuration. The selection method of the stability factor was investigated considering the trade-off relation between spatial resolution and noise amplification or array gain. The suggested method was applied to the problems of both microphone- and loudspeaker arrays to obtain a specific directivity pattern of high resolution with a constant beamwidth.
Convention Paper 8401 (Purchase now)

P14-3 Design 3-D High Order Ambisonics Encoding Matrices Using Convex OptimizationHaohai Sun, U. Peter Svensson, Norwegian University of Science and Technology - Trondheim, Norway
In this paper we propose a convex optimization method for the design of 3-D High Order Ambisonics (3-D HOA) encoding matrices using spherical microphone arrays, which offers the possibility to impose spatial stop-bands in the directivity patterns of all the spherical harmonics while keeping the transformed audio channels still compatible with the 3-D HOA reproduction sound format. Using the proposed convex optimization method, the globally optimal encoding matrices can be obtained, and the suitable trade-off among several design factors, e.g., response distortions in the obtained spherical harmonic, the dynamic range of matrix coefficients, i.e., the system robustness, and frequencies, can be analyzed and illustrated. The proposed convex optimization is formulated as a form of second-order cone programming that can be efficiently solved. Numerical results validate the proposed method. This method can be easily generalized to the 2-D HOA cases.
Convention Paper 8402 (Purchase now)

P14-4 Principles in Surround Recordings with HeightGuenther Theile, VDT - Geretsried, Germany; Helmut Wittek, Schoeps Mikrofone - Karlsruhe, Germany
New multichannel sound formats extending 5.1 with height channels are adding the third dimension to recordings. They provide a much wider range of spatial sound effects and allow more realism of spatial reproduction in terms of direct sound, early and late reflections, reverberation, and ambience sound. Using the example of two upper layer front and two upper layer surround complementary loudspeakers (5.1+4, known as “Auro 3D 9.1”) the psychoacoustic principles in the perception of elevated phantom sound sources, spatial depth, spatial impression, envelopment, ambient atmosphere, as well as directional stability within the sweet area are discussed. Concrete proposals for microphone configurations can evolve from these considerations.
Convention Paper 8403 (Purchase now)

P14-5 Efficient 3-D Sound Field ReproductionMincheol Shin, Filippo Fazi, ISVR, University of Southampton - Southhampton, UK; Jeongil Seo, Electronics Telecommunication Research Institute - Daejeon, Korea; Philip A. Nelson, ISVR, University of Southampton - Southampton, UK
A method is presented for efficient sound field reproduction with a loudspeaker array constituted by multiple sound sources that are three-dimensionally distributed. The physical reproduction of several target sound fields is investigated when the target sound fields are surrounded by multiple sound sources. A cost function to be minimized has been developed to obtain the optimal solution with reasonable energy distribution and sufficient sweet area when the distribution of loudspeakers is non-uniform. The performance of the proposed method is verified by the results of computer simulations and subjective tests in the cases of NHK 22.2 and ETRI 10.2 channel configurations.
Convention Paper 8404 (Purchase now)

P14-6 On the Scattering of Synthetic Sound FieldsJens Ahrens, Sascha Spors, Deutsche Telekom Laboratories, Technische Universität Berlin - Berlin, Germany
In sound field synthesis a given arrangement of elementary sound sources is employed in order to synthesize a sound field with given desired physical properties over an extended region. The calculation of the driving signals of these secondary sources typically assumes free-field propagation conditions. The present paper investigates the scattering of such synthetic sound fields from unavoidable scattering objects like the head and body of a person apparent in the target region. It is shown that the basic mechanisms are similar to the scattering of natural sound fields. Though, synthetic sound fields can exhibit properties different to those of natural sound fields. Consequently, in such cases also the scattered synthetic sound fields exhibit properties different to those of scattered natural sound fields.
Convention Paper 8405 (Purchase now)

P14-7 Toward Mass-Customizing Up/Down Generic 3-D Sounds for Listeners: A Pilot Experiment Concerning Inter-Subject VariabilityJohn Au, Richard So, Andrew Horner, The Hong Kong University of Science & Technology - Clearwater Bay, Kowloon, Hong Kong
The “delay-and-add” theory (Hebrank and Wright, 1974) was used to calculate 4068 matching scores between each of the 192 HRTFs and the dimensions of 12 pairs of ears for two incident sound directions (30 degrees up and 30 degrees down). Five HRTFs with 0, 25, 50, 75, and 100th percentile average matching scores were selected for two incident directions. These 10 HRTFs were used to produce 10 sound cues (5 from 30 degrees up and 5 from 30 degrees down). Ten listeners participated in a sound localization experiment to localize the 10 sound cues presented in random order and with 5 repetitions. Preliminary results indicated that matching scores can explain up to 22% of the inter-subject variations in localization errors. Potential applications are discussed.
Convention Paper 8406 (Purchase now)

P15 - Speech and Coding


Sunday, May 15, 11:30 — 13:00 (Room: Foyer)

P15-1 A New Robust Hybrid Acoustic Echo Cancellation Algorithm for Speech Communication in Car EnvironmentsYi Zhou, Chengshi Zheng, Xiaodong Li, Chinese Academy of Sciences - Beijing, China
This paper studies a new robust hybrid adaptive filtering algorithm for acoustic echo cancellation (AEC) in a car speech communication system. The proposed algorithm integrates the affine projection algorithm (APA) and normalized least mean square (NLMS) algorithm. It can switch between them with a coefficient derivative-based technique to achieve overall optimum convergence performance. To help the algorithm combat deteriorating impulsive interferences widely encountered in car environments and enhance the system robustness in double talk period, robust statistics technique is also incorporated into the proposed algorithm. Experiments are conducted to verify the improved and robust overall AEC convergence performance achieved by the new algorithm.
Convention Paper 8407 (Purchase now)

P15-2 Speech Source Separation Using a Multi-Pitch Harmonic Product Spectrum-Based AlgorithmRehan Ahmed, Roberto Gil-Pita, David Ayllón, Lorena Álvarez, University of Alcalá - Alcalá de Henares, Spain
This paper presents an efficient algorithm for separating speech signals by determining multiple pitches from mixtures of signals and assigning the sources to one of those estimated pitches. The pitch detection algorithm is based on Harmonic Product Spectrum. Since the pitch of speech signals fluctuates readily, a frame-based algorithm is used to extract the multiple pitches in each frame. Then, the fundamental frequency (pitch) for each source is estimated and tracked after comparing all the frames. The estimated fundamental frequency of the sources is then used to generate a set of binary masks that allow separating the signals in the Short Time Fourier Transform domain. Results show a considerable separation of the speech signals, justifying the feasibility of the proposed method.
Convention Paper 8408 (Purchase now)

P15-3 User-Orientated Subjective Quality Assessment in the Case of Simultaneous InterpretersJudith Liebetrau, Thomas Sporer, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Paolo Tosoratti, DG Interpretation - Brussels, Belgium; Daniel Fröhlich, Sebastian Schneider, Jens-Oliver Fischer, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany
A study was conducted to explore various subjective quality aspects of audio-visual systems for interpreters. The study was designed to bring the existing requirements for on-site simultaneous interpretation up-to-date and to specify new requirements for remote interpretation (teleconferencing). The feasibility of using objective measurement methods in this context was examined. Several parameters influencing perceived quality, such as audio coding, video coding, room characteristics, and audio-visual latency were assessed. The results obtained are partially contradictory to previous studies. This leads to the conclusion that perceived quality is strongly linked to the focus, background, and abilities of the assessors. The test design, realization, and obtained results are shown, as well as a comparison to studies conducted with different types of users.
Convention Paper 8409 (Purchase now)

P15-4 Analysis of Parameters of the Speech Signal Loudness of Professional Television AnnouncersMirjana Mihajlovic, Radio Television of Serbia - Belgrade, Serbia; Dejan Todorovic, Radio Belgrade - Belgrade, Serbia; Iva Salom, Institute Mihajlo Pupin - Belgrade, Serbia
The paper analyzes speech loudness of professional announcers, who do large percentage of television audio signals. Over 100 files of speech signals recorded with same equipment were analyzed. For each file the authors calculated loudness and true peak, according to ITU-R BS 1770 and EBU R128 and RMS. There were criteria adopted for classification of records, and results were statistically analyzed. Analysis showed that the loudness of the speech signal depends on the gender of speakers, intonation, and type of program material, and also that files of greater loudness may not always have higher peak value to files of lower loudness. It was noted there was a significant overlap among the short-term loudness and RMS values calculated with the same time constant.
Convention Paper 8410 (Purchase now)

P15-5 Improved Prediction of Nonstationary Frames for Lossless Audio CompressionFlorin Ghido, Tampere University of Technology - Tampere, Finland
We present a new algorithm for improved prediction of nonstationary frames for asymmetrical lossless audio compression. Linear prediction is very efficient for decorrelation of audio samples, however it requires segmentation of the audio into quasi-stationary frames. Adaptive segmentation tries to minimize the total compressed size, including the quantized prediction coefficients for each frame, thus longer frames that are not quite stationary may be selected. The new algorithm for computing the linear prediction coefficients improves compressibility of nonstationary frames when compared with the least squares method. With adaptive segmentation, the proposed algorithm leads to small but consistent compression improvements up to 0.56%, on average 0.11%. For faster encoding using fixed size frames, without including adaptive segmentation, it significantly reduces the penalty on compression with more than 0.21% on average.
Convention Paper 8411 (Purchase now)

P15-6 A Lossless/Near-Lossless Audio Codec for Low Latency Streaming Applications on Embedded DevicesNeil Smyth, Cambridge Silicon Radio - Belfast, Northern Ireland
Increasingly there is a need for high quality audio streaming in devices such as modular home audio networking systems, PMPs, and wireless loudspeakers. As wireless transmission capacities continue to increase it is desirable to utilize this increasing data bandwidth to perform real-time wireless streaming of audio content coded in a lossless or near-lossless format. In this paper we discuss the development of an adaptive audio coding algorithm that balances the design goals of low latency, low complexity, error robustness, and a dynamically-variable bit rate that scales to mathematically-lossless coding under suitable conditions. Particular emphasis is placed on the optimization of the algorithm structure for real-time audio processing applications and the mechanism by which "hybrid" lossless and near-lossless coding is achieved.
Convention Paper 8412 (Purchase now)

P15-7 Low-Delay Directional Audio Coding for Real-Time Human-Computer InteractionTapani Pihlajamäki, Ville Pulkki, Aalto University School of Electrical Engineering - Espoo, Finland
Games and virtual worlds require low-cost, good-quality, and low-delay audio engines. The short-time Fourier transform- (STFT) based implementation of Directional Audio Coding (DirAC) for virtual worlds fulfills the two first demands. Unfortunately, the delay can be perceivably large. In this paper, a modification to DirAC is introduced that uses different time-frequency resolutions for STFT concurrently, which are not aligned in time in reproduction. This leads to the high-frequency non-diffuse content being reproduced as soon as possible and thus reduces the perceived delay. Informal tests show that the delay was short enough for a musician to play an instrument through the processing. Moreover, the results of formal listening tests show that the reduction in quality is perceptible but not annoying.
Convention Paper 8413 (Purchase now)

P16 - Audio Signal Processing and Analysis


Sunday, May 15, 14:00 — 17:30 (Room 1)

Chair:
Jayant Datta

P16-1 A New Approach to Designing Decimation Filters for Oversampled A/D ConvertersJamie A. S. Angus, University of Salford - Salford, Greater Manchester, UK
This paper presents a new approach to designing the necessary decimation filter in over-sampled noise shaping analog to digital converters. These filters are still finite impulse response designs but they are designed using novel window functions that produce a stop-band attenuation that increases with frequency thus matching the out of band noise characteristics of the noise-shaping modulator. As a result high quality decimation filters can be realized using shorter filter lengths.
Convention Paper 8414 (Purchase now)

P16-2 Warped IIR Filter Design with Custom Warping Profiles and its Application to Room Response Modeling and EqualizationBalázs Bank, Budapest University of Technology and Economics - Budapest, Hungary
In traditional warped FIR and IIR filters, the frequency-warping profile is adjusted by a single free parameter, leading to a less flexible allocation of frequency resolution. As an example, it is not possible to achieve a truly logarithmic frequency resolution, which would be often desired in audio applications. In this paper a new approach is presented for warped IIR filter design where the filter specification is transformed by any desired (e.g., logarithmic) frequency transformation, and a standard IIR filter is designed to this transformed specification. Then, the poles and zeros of this transformed filter are found and mapped back to the original frequency scale. Due to the approximations in mapping back the poles and zeros, the resulting transfer function may show some discrepancies from its optimal version. This is resolved by an additional optimization of the zeros of the final filter. Examples of loudspeaker-room response modeling and equalization are presented.
Convention Paper 8415 (Purchase now)

P16-3 Computationally Efficient Nonlinear Chebyshev Models Using Common-Pole Parallel Filters with the Application to Loudspeaker ModelingBalázs Bank, Budapest University of Technology and Economics - Budapest, Hungary
Many audio systems show some form of nonlinear behavior that has to be taken into account in modeling. For this, often a black-box model is identified, coming from the generality and simplicity of this approach. One such model is the simplified Volterra model, using parallel branches that have a polynomial-type nonlinearity and a linear filter in series. For example, Chebyshev models use Chebyshev polynomials as nonlinear functions, making the model identification a very straightforward procedure by using logarithmic sweep measurements. This paper proposes a highly efficient implementation of Chebyshev models by using fixed-pole parallel filters for the linear filtering part. The efficiency comes from the fact that parallel filters can have a logarithmic frequency resolution, which better fits the human hearing behavior than traditional FIR or IIR filters. Moreover, the branches can share the same denominators, leading to an additional performance benefit. The proposed model is particularly well suited for the real-time digital simulation of loudspeakers and other weakly nonlinear devices, such as tube guitar amplifiers.
Convention Paper 8416 (Purchase now)

P16-4 Event-Driven Real-Time Audio Processing with GPGPUsTiziano Leidi, Thierry Heeb, Marco Colla, ICIMSI-SUPSI - Manno, Switzerland; Jean-Philippe Thiran, EPFL - Lausanne, Switzerland
Development of real-time audio processing applications for GPGPUs is not without challenges. Parallel processing of audio signals is often constrained by serial dependencies within or between the algorithms. On GPGPUs, insufficient data pressure further limits the attainable performance improvements, as it causes inactivity of the GPU cores. In this paper we analyze the limits of audio processing on GPGPUs and present an approach based on event-driven scheduling, that maximizes data pressure to favor performance improvements. We also present recent enhancements of Audio n-Genie, an open-source development environment for audio-processing applications. By combining Audio n-Genie and the proposed approach, we show that it is possible to increase audio processing speed-up.
Convention Paper 8417 (Purchase now)

P16-5 A Comparison of Parametric Optimization Techniques for Tone MatchingMatthew Yee-King, Goldsmiths, University of London - London, UK; Martin Roth, Reality Jockey, Ltd. - London, UK
Parametric optimization techniques are compared in their abilities to elicit parameter settings for sound synthesis algorithms, which cause them to emit sounds as similar as possible to target sounds. A hill climber, a genetic algorithm, a neural net, and a data driven approach are compared. The error metric used is the Euclidean distance in MFCC feature space. This metric is justified on the basis of its success in previous work. The genetic algorithm offers the best results with the FM and subtractive test synthesizers but the hill climber and data driven approach also offer strong performance. The concept of sound synthesis error surfaces, allowing the detailed description of sound synthesis space, is introduced. The error surface for an FM synthesizer is described and suggestions are made as to the resolution required to effectively represent these surfaces. This information is used to inform future plans for algorithm improvements.
Convention Paper 8418 (Purchase now)

P16-6 On the Multichannel Sinusoidal Model for Coding Audio Object SignalsToni Hirvonen, Institute of Computer Science, Foundation for Research and Technology–Hellas (FORTH-ICS) Heraklion - Crete, Greece (now with Dolby Laboratories, Stockholm, Sweden); Athanasios Mouchtaris, Institute of Computer Science, Foundation for Research and Technology–Hellas (FORTH-ICS), Heraklion - Crete, Greece, and University of Crete, Heraklion, Crete, Greece
This paper presents two improvements on a recently proposed multichannel sinusoidal modeling system for coding multiple audio object signals. The system includes extracting the sinusoidal components and an LPC envelope for each object signal, as well as transform coding of the residuals' downmix. The contributions of this paper are: (a) a psychoacoustic model for enabling the system to scale well with multiple object signals, and (b) an improved method to encode the common residual, tailored to the "white" nature of this signal. As a result, sound quality of around 90% on the MUSHRA scale is obtained for 10 simultaneous object signals coded with a total rate of 150 kbit/s, while retaining the individual object parametric representations.
Convention Paper 8419 (Purchase now)

P16-7 An Additive Synthesis Technique for Independent Modification of the Auditory Perceptions of Brightness and WarmthAsteris Zacharakis, Joshua Reiss, Queen Mary University of London - London, UK
An algorithm that achieves independent modification of two low-level features that are correlated with the auditory perceptions of brightness and warmth was implemented. The perceptual validity of the algorithm was tested through a series of listening tests in order to examine whether the low-level modification was indeed perceived as independent and to investigate the influence of the fundamental frequency on the perceived modification. A Multidimensional Scaling analysis (MDS) on listener responses to pairwise dissimilarity comparisons accompanied by a verbal elicitation experiment examined the perceptual significance and independence of the two low-level features chosen. This is a first step for the future development of a perceptually based control of an additive synthesizer.
Convention Paper 8420 (Purchase now)

P17 - Binaural and Spatial Audio


Sunday, May 15, 14:00 — 15:30 (Room: Foyer)

P17-1 Repeatability of Localization Cues in HRTF Data BasesElena Blanco-Martin, Silvia Merino Saez-Miera, Juan José Gomez-Alfageme, Luis Ignacio Ortiz-Berenguer, Universidad Politecnica de Madrid - Madrid, Spain
Head Related Transfer Function (HRTF) represents the time-spectral filtering that head and torso do to a sound that goes from a sound source to the ears. These transfer functions bring the localization cues that vary according to sound source position (azimuth and elevation). Human auditory system uses such localization cues for estimating the sound direction. HRTF are used in two ways. One way is for synthesizing binaural sound (virtual audio 3-D). The second way is for analyzing binaural sounds in order to estimate the localization of sound sources. Therefore HRTF are important and useful data for researchers. There are few public HRTF data bases. The most known is the Kemar Data Base from MIT. There is also the Cipic Data Base from UC Davis and the Itakura Data Base. In this paper we present a new public data base for researching use available on the web. The data base has been measured on the Head and Torso Simulator 4100 by Bru¨el & Kjær. In addition, a comparative study of localization cues from the data bases is carried out for showing their repeatability.
Convention Paper 8421 (Purchase now)

P17-2 Dynamic Head-Related Transfer Function Measurement Using a Dual-Loudspeaker ArrayQinghua Ye, Qiujie Dong, Lingling Zhang, Xiaodong Li, Institute of Acoustics, Chinese Academy of Sciences - Beijing, China
A dynamic Head-Related Transfer Function (HRTF) measurement method using a dual-loudspeaker array is presented, which reduces measuring requirements and increases the efficiency as well. First, the dual-loudspeaker array emits uncorrelated signals, while head size and head motion are obtained through short-time time-delay estimation. Second, in the approximation of linear time-invariant (LTI) within the testing time, multi-point continuous HRTF measurement is accomplished. Compared with FASTRAK head tracking system, the experimental results confirm the validity of the proposed method.
Convention Paper 8422 (Purchase now)

P17-3 Statistical Analysis of Binaural Room Impulse ResponsesEleftheria Georganti, Alexandros Tsilfidis, John Mourjopoulos, University of Patras - Patras, Greece
In previous work of the authors, the spectral magnitude of room transfer functions (RTFs) was analyzed using histograms and statistical quantities (moments), such as the kurtosis and skewness. In this paper the above analysis is extended to binaural room impulse responses (BRIRs) and the dependence of the statistical measures on the room acoustical properties, such as the reverberation time, the room size, and the source-receiver distance is discussed. Emphasis is given on the binaural measure of the magnitude squared coherence (MSC), which is considered to be an important cue for binaural hearing related to perceptual aspects such as the source width, the envelopment and the spaciousness. After a brief overview of the existing MSC models, a perceptually-motivated MSC implementation is examined, based on a gammatone filterbank. MSC results for various rooms and source-receiver positions are presented and related to the existing MSC models.
Convention Paper 8423 (Purchase now)

P17-4 Spatial Sound and Stereoscopic VisionPaul Mannerheim, University of California, Santa Barbara - Santa Barbara, CA, USA
This paper presents a technique for reproducing coherent audio visual images for multiple users, only wearing 3-D glasses and without utilizing head racking. The recent emergence of 3-D content has increased the demand for technology that can display visual images that are coherent with sound images for multiple users. Audio visual object difference is here investigated for analyzing the size of the sweet spot of a system that combines a visual display technique named stereoscopy with a sound reproduction technique called wave field synthesis. The sweet spot of such a configuration is limited due to differences in characteristics between the sound reproduction system and the visual display; however as a consequence, it is found that the number sources in the wave field synthesis array can be reduced.
Convention Paper 8424 (Purchase now)

P17-5 Designing Ambisonic Decoders for Improved Surround Sound Playback in Constrained Listening SpacesDavid Moore, Glasgow Caledonian University - Glasgow, Scotland, UK; Jonathan Wakefield, University of Huddersfield - Huddersfield, UK
Much research has been undertaken to optimize irregular 5-speaker Ambisonic decoders for idealized listening environments. In such environments loudspeaker placement is not restricted and can conform to the ITU 5.1 standard. In domestic settings, the room shape, furniture, and television positioning often restrict speaker placement. It is often the case that a compromised speaker layout is enforced by other domestic requirements. This paper seeks to derive Ambisonic decoders to optimize perceived localization performance for these constrained asymmetrical speaker layouts. This work uses a heuristic search algorithm to derive decoder coefficients and simultaneously optimize loudspeaker angle within specified bounds. Theoretical results are shown for different orders of newly derived Ambisonic decoders for typical domestic scenarios.
Convention Paper 8425 (Purchase now)

P17-6 Decoding for 3-DJohannes Boehm, Technicolor, Research & Innovation - Hannover Germany
Three dimensional spatial sound reproduction using irregular loudspeaker layouts requires a special decoder design. We present the fundamentals of Higher Order Ambisonics (HOA) decoding. Then we focus on beam forming techniques to derive solutions for irregular spaced setups. Panning functions are created by vector base amplitude panning or least-squares methods as patterns and are modeled by spherical harmonics. The required HOA order for effective beam forming proves to be in inverse proportion to the minimal angular spacing of speakers. We demonstrate decoder design using an example setup of 16 speakers, and evaluate objective performance criteria. We conclude that decoders for irregular setups require higher HOA orders compared to decoders for regular setups using the same number of speakers and discuss the consequences.
Convention Paper 8426 (Purchase now)

P17-7 Real-Time Reproduction of Moving Sound Sources by Wave Field Synthesis: Objective and Subjective Quality EvaluationMichele Gasparini, Paolo Peretti, Stefania Cecchi, Laura Romoli, Francesco Piazza, Universita Politecnica delle Marche - Ancona, Italy
Wave Field Synthesis (WFS) is an audio rendering technique that allows the reproduction of an acoustic image over an extended listening area. In order to achieve a realistic sensation, true representation of moving sound sources is essential. In this paper a real time algorithm that significantly reduces computational efforts in the synthesis of WFS driving functions in presence of moving sound sources is presented. High efficiency can be obtained taking into account a model based on phase approximation and Short Time Fourier Transform (STFT). The influence of the streaming frame size and of the source velocity on well known sound field artifacts has been studied, considering PC simulations and listening tests.
Convention Paper 8427 (Purchase now)

P17-8 Assessing Diffuse Sound Field Reproduction Capabilities of Multichannel Playback SystemsAndreas Walther, Christof Faller, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland
The generation of subjectively diffuse sound fields is an essential part of creating pleasing synthetic sound fields using loudspeaker playback. A number of studies have been published presenting subjective evaluations of the diffuse sound field reproduction capabilities of different loudspeaker setups. We present a model, based on interaural coherence and interaural level difference, for estimating perceived diffuseness of synthetic sound fields evoked by an arbitrary number of transducers at different positions. The results of different loudspeaker setups and listener orientations are compared.
Convention Paper 8428 (Purchase now)

P18 - Source Enhancement


Monday, May 16, 09:00 — 13:00 (Room 1)

Chair:
John Mourjopoulos

P18-1 Dereverberation in the Spatial Audio Coding DomainMarkus Kallinger, Giovanni Del Galdo, Fabian Kuech, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Oliver Thiergart, International Audio Laboratories - Erlangen, Germany
Spatial audio coding techniques are fundamental for recording, coding, and rendering spatial sound. Especially in teleconferencing, spatial sound reproduction helps in making a conversation feel more natural reducing the listening effort. However, if the acoustic sources are far from the microphone arrangement, the rendered sound may easily be corrupted by reverberation. This paper proposes a dereverberation technique, which is integrated efficiently into the parameter domain of Directional Audio Coding (DirAC). Utilizing DirAC’s signal model we derive a parametric method to reduce the diffuse portion of the recorded signal. Instrumental quality measures and informal listening tests confirm the efficiency of the proposed method to render a spatial sound scene less reverberant without introducing noticeable artifacts.
Convention Paper 8429 (Purchase now)

P18-2 Blind Single-Channel Dereverberation for Music Post-ProcessingAlexandros Tsilfidis, John Mourjopoulos, University of Patras - Patras, Greece
Although dereverberation can be useful in many audio applications, such techniques often introduce artifacts that are unacceptable in audio engineering scenarios. Recently, the authors have proposed a novel dereverberation approach, suitable for both speech and music signals, based on perceptual reverberation modeling. Here, the method is fine-tuned for sound engineering applications and tested for both natural and artificial reverberation. The results show that the proposed technique efficiently suppresses reverberation without introducing significant processing artifacts and the method is appropriate for the post-processing of music recordings.
Convention Paper 8430 (Purchase now)

P18-3 Joint Noise and Reverberation Suppression for Speech ApplicationsElias K. Kokkinis, Alexandros Tsilfidis, Eleftheria Georganti, John Mourjopoulos, University of Patras - Patras, Greece
An algorithm for joint suppression of noise and reverberation from speech signals is presented. The method requires a handclap recording that precedes speech activity. A running kurtosis technique is applied in order to extract an estimation of the late reflections of the room impulse response from the clap while a moving average filter is employed for the noise estimation. Moreover, the excitation signal derived from the Linear Prediction (LP) analysis of the noisy speech along with the estimated power spectrum of the late reflections are used to suppress late reverberation through spectral subtraction while a Wiener filter compensates for the ambient noise. A gain magnitude regularization step is also implemented to reduce overestimation errors. Objective and subjective results show that the proposed method achieves significant speech enhancement in all tested cases.
Convention Paper 8431 (Purchase now)

P18-4 System Identification for Acoustic Echo Cancellation Using Stepped Sine Method Related to FFT SizeTaeJin Park, Seung Kim, Koeng-mo Sung, Seoul National University - Seoul, Korea
A stepped sine method was applied for system identification to cancel acoustic echoes in a speaker phone system that has been widely used in recent mobile devices. We applied the stepped sine method by regarding Discrete Fourier Transform (DFT) as a uniform-DFT filter bank. By using this stepped sine method, we were able to obtain more accurate and detailed characteristics of non-linearity, dependent on the amplitude and frequency of speech. We stored the non-linearity information into linear transform matrices and estimated the responses of the mobile device speaker. The proposed method exhibits higher echo return loss enhancement (ERLE) and increased correlation when compared to the conventional method.
Convention Paper 8432 (Purchase now)

P18-5 Using Spaced Microphones with Directional Audio CodingMikko-Ville Laitinen, Aalto University - Espoo, Finland; Fabian Kuech, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Ville Pulkki, Aalto University - Espoo, Finland
Directional audio coding (DirAC) is a perceptually motivated method to reproduce spatial sound, which typically uses input from first-order coincident microphone arrays. This paper presents a method to additionally use spaced microphone setups with DirAC. It is shown that since diffuse sound is incoherent between spatially separated microphones at certain frequencies, no decorrelation in DirAC processing is needed, which improves the perceived quality. Furthermore, the directions of sound sources are perceived to be more accurate and stable.
Convention Paper 8433 (Purchase now)

P18-6 Parameter Estimation in Directional Audio Coding Using Linear Microphone ArraysOliver Thiergart, International Audio Laboratories - Erlangen, Germany; Michael Kratschmer, Markus Kallinger, Giovanni Del Galdo, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
Directional Audio Coding (DirAC) provides an efficient description of spatial sound in terms of few audio downmix signals and parametric side information, namely the Direction Of Arrival (DOA) and the diffuseness of the sound. Traditionally, the parameters are derived based on the active sound intensity vector that is often determined via 2-D or 3-D microphone grids. Adapting this estimation strategy to linear arrays, which are preferred in various applications due to form factor constraints, yields comparatively poor results. This paper proposes to replace the intensity based DOA estimation in DirAC by a specific estimation of signal parameters via rotational invariant techniques, namely ESPRIT. Moreover, a diffuseness estimator exploiting the correlation between the array sensors is presented. Experimental results show that the DirAC concept can be applied in practice also in conjunction with linear arrays.
Convention Paper 8434 (Purchase now)

P18-7 Extraction of Voice from the Center of the Stereo ImageAki Härmä, Munhum Park, Philips Research Laboratories Eindhoven - Eindhoven, The Netherlands
Detection and extraction of the center vocal source is important for many audio format conversion and manipulation applications. First, we study some generic properties of stereo signals containing sources panned exactly to the center of the stereo image and propose an algorithm for the separation of a stereo audio signal into a center and side channels. In the 128th AES Convention a paper was presented (Convention Paper 8071) on listening tests comparing the perception of the widths of the stereo images of synthetic signal combinations. In this paper the same experiment is repeated with real stereo audio content using the proposed center separation algorithm. The main observation is that there are clear differences in the results. The reasons for the differences are discussed in light of the literature and analysis of the test signals and their binaural characteristics in the listening test setup.
Convention Paper 8435 (Purchase now)

P18-8 Directional Segmentation of Stereo Audio via Best Basis Search of Complex Wavelet PacketsJeremy Wells, University of York - York, North Yorkshire, UK
A system for dividing time-coincident stereo audio signals into directional segments is presented. The purpose is to give greater flexibility in the presentation of spatial information when two-channel audio is reproduced. For example, different inter-channel time shifts could be introduced for segments depending on their direction. A novel aspect of this work is the use of complex wavelet packet analysis, along with “best basis” selection, in an attempt to identify time-frequency atoms that belong to only one segment. The system is described, with reference to the relevant underlying theory, and the quality of its output for the best bases from complex wavelet packets is compared with methods based on more established analysis and processing methods.
Convention Paper 8436 (Purchase now)

P19 - Room Acoustics


Monday, May 16, 09:00 — 10:30 (Room: Foyer)

P19-1 System Identification of Equalized Room Impulse Responses by an Acoustic Echo Canceller Using Proportionate LMS AlgorithmsStefan Goetze, Feifei Xiong, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Jan Ole Jungmann, University of Lübeck - Lübeck, Germany; Markus Kallinger, University of Oldenburg - Oldenburg, Germany (now with Franhofer Institute for Integrated Circuits IIS, Erlangen, Germany); Karl-Dirk Kammeyer, University of Bremen - Bremen, Germany; Alfred Mertins, University of Lübeck - Lübeck, Germany
Hands-free telecommunication systems usually employ subsystems for acoustic echo cancellation (AEC), listening-room compensation (LRC), and noise reduction in combination. This contribution discusses a combined system of a two-stage AEC filter and an LRC filter to remove reverberation introduced by the listening room. An inner AEC is used to achieve initial echo reduction and to perform system identification needed for the LRC filter. An additional outer AEC is used to further reduce the acoustic echoes. The performance of proportionate filter update schemes such as the so-called proportionate normalized least mean squares algorithm (PNLMS) or the improved PNLMS (IPNLMS) for system identification of equalized impulse response (IR) are shown and the mutual influences of the subsystems are analyzed. If the LRC filter succeeds in shaping a sparse overall IR for the concatenated system of LRC filter and room impulse response (RIR) the PNLMS performs best since it is optimized for the identification of sparse IRs. However, the equalization may be imperfect due to channel estimation errors in periods of convergence and due to the so-called tail-effect of AEC, i.e., the fact that only the first part of a RIR is identified in practical systems. The IPNLMS is more appropriate in this case to identify the equalized IR.
Convention Paper 8437 (Purchase now)

P19-2 Virtual Room Acoustics : A Comparison of Techniques for Computing 3-D-FDTD Schemes Using CUDACraig Webb, Stefan Bilbao, University of Edinburgh - Edinburgh, Scotland, UK
High fidelity virtual room acoustics can be approached through direct numerical simulation of wave propagation in a defined space. Three-dimensional Finite Difference Time Domain schemes can be employed and adept well to a parallel programming model. This paper examines the various approaches for calculating these schemes using the Nvidia CUDA architecture. We test the different possibilities for structuring computation, based on the available memory objects and thread-blocking model. A standard test simulation is computed at double precision under different arrangements. We find that a 2-D extended tile blocking system, combined with shared memory usage, produces the fastest computation for our scheme. However, shared memory usage is only marginally faster than direct global memory access, using the latest FERMI GPUs.
Convention Paper 8438 (Purchase now)

P19-3 Acoustic Parameters of Chosen Orthodox Churches Overview and Preliminary Psychoacoustic Tests Using Choral MusicPawel Maleck, Jerzy Wiciak, AGH University of Science and Technology - Kraków, Poland
A lot of acoustic research was done for Roman Catholic churches and because of some differences in traditions and culture comparing to Orthodoxy, it is not the best idea to use its acoustic estimators for Orthodox churches. The paper shows results of measurements in some Orthodox churches in Poland and the proposal of psychoacoustic tests using the convolution technique, which would allow formulating the new acoustic outlines for Orthodox churches. The research has been done especially considering choral music, which is an inseparable part of Eastern Christian culture; so as a test, there were Orthodox choir sound samples recorded in an anechoic chamber convoluted with impulse response of measured churches.
Convention Paper 8439 (Purchase now)

P19-4 A Comparative Study of Various “Optimum” Room Dimension RatiosJohn Sarris, Aretaieio University Hospital - Athens, Greece
Various “optimum” room dimension ratios that have been proposed in the literature are studied and compared. Since each proposal is based on a different criterion, independent objective measures of the acoustic quality of the various room ratios are applied in this paper. The most straightforward metric is the flatness of a room’s corner to corner frequency response, but since this is not representative of the variations of the sound pressure within the closed space, different metrics are employed to quantify these variations. Simulation results are presented to evaluate the effectiveness of the various ratios for the case of a small and a larger room.
Convention Paper 8440 (Purchase now)

P19-5 Perception of Spatial Distribution of Room Response Reproduced Using Different Loudspeaker SetupsJavier Gomez, Aalto University - Espoo, Finland; Rafael C. D. Paiva, Aalto University - Espoo, Finland, Nokia Technology Institute INdT, Brazil; Kai Saksela, Thomas Svedström, Ville Pulkki, Aalto University - Espoo, Finland
A listening test was conducted to assess the effect that different direct-to-reverberant ratios, loudspeaker setups, and reverberation times have on the directional perception of a synthetic room response. The results show that the perceived spatial distribution of reverberation is dependent on the speaker setup, on the reverberation time, and on the listener. Additionally, they show that a small amount of direct sound, even when barely masked by reverberation, shifts the overall perception to the front.
Convention Paper 8441 (Purchase now)

P19-6 Modal Analysis and Sound Field Simulation of Vibration Panels in a Free Sound Field and in a Rectangular EnclosureKazuhiko Kawahara, Akihiro Sonogi, Kyushu University - Fukuoka, Japan; Shin-ya Sato, Kyushu University - Fukuoka, Japan, Nittobo Acoustic Engineering Co., Ltd., Tokyo, Japan
Several types of implementation of panel loudspeakers, for example, distributed mode loudspeaker (DML), are proposed. The diaphragm of a DML is thought to behave like a bending plate. The diaphragm of an electrostatic loudspeaker is thought move as a rigid plate. What is the difference of an acoustical sound field generation feature with each implementation? In this paper we used models of same dimensional rectangular panel. One is a rigid diaphragm. Another is a bending panel that has an actuator in the center of it. We made simulations of directivity and sound pressure distribution in a rectangular room. We made simulations of sound pressure distribution in a rectangular room. We could show less coherent SPL distribution in the case of a bending panel.
Convention Paper 8442 (Purchase now)

P19-7 Simple Room Acoustic Analysis Using a 2.5 Dimensional ApproachPatrick Macey, PACSYS Limited - Nottingham, UK
Cavity modes of a finite bounded region with rigid boundaries can be used to compute the steady state harmonic response for excitation of an acoustic cavity by a point source. In Cuboid domains, with analytical modes, this is straightforward. For more general regions, determining a set of orthonormal modes is more difficult. The finite element method could be used for arbitrary 3-D regions. The current work investigates a hybrid numerical/analytical method, applicable to rooms of constant height, but arbitrary cross section. A 2-D FE analysis is used to compute the cross-section modes/frequencies. Three-dimensional modes are constructed as an outer product of the cross section modes and 1-D modes for the height. Comparison is made with BEM computations.
Convention Paper 8443 (Purchase now)

P19-8 Early Reflections Design for Natural Stereo Sound ListeningChul-Jae (Jay) Yoo, RADSONE, Inc. - Gyeonggi-do, Korea
For natural stereo sound in rooms, some considerations must be followed. For example, to maximize time density, Feedback Delay Network (FDN) is used in which the feedback matrix has every element consisting of absolute value 1. To model faster high frequency decay according to the increasing number of reflections, absorption filters after delay lines in the FDN are generally used. Mixing matrix for uncorrelated L/R output is also used. In this paper an elaborate design scheme of the first early reflection portion in early reflections was proposed to obtain higher IACC values than those of conventional systems, resulting in a more precise sound source image with ambience.
Convention Paper 8444 (Purchase now)

P20 - Subjective Evaluation


Monday, May 16, 14:00 — 16:00 (Room 1)

Chair:
Bruno Fazenda

P20-1 Selection of Audio Stimuli for Listening TestsJonas Ekeroot, Jan Berg, Arne Nykänen, Luleå University of Technology - Luleå, Sweden
Two listening test methods in common use for the subjective assessment of audio quality are the ITU-R recommendations BS.1116-1 for small impairments and BS.1534-1 (MUSHRA) for intermediate quality. They stipulate the usage of only critical audio stimuli (BS.1116-1) to reveal differences among systems under test, or critical audio stimuli that represents typical audio material in a specific application context (MUSHRA). A poor selection of stimuli can cause experimental insensitivity and introduce bias, leading to inconclusive results. At the same time this selection process is time-consuming and labor-intensive, and is difficult to conduct in a systematic way. This paper reviews and discusses the selection of audio stimuli in listening test-related studies.
Convention Paper 8445 (Purchase now)

P20-2 A Listening Test System for Automotive Audio: PART 5 – The Influence of Listening Environment on the Realism of Binaural ReproductionFrancois Postel, Bang & Olufsen A/S - Struer, Denmark (now at Arkamys, Paris, France), Department of Mechanical Vibrations and Acoustics, UTC, Compiegne, France; Patrick Hegarty, Søren Beck, Bang & Olufsen A/S - Struer, Denmark
Binaural technology is used to capture elements of an in-car sound field and reproduce them over headphones at another place and time. An experiment to test the influence of the listening environment on the realism of such a binaural reproduction is described. A panel of 12 trained listeners rated a range of stimuli for 6 elicited attributes of sound quality. Ratings are made for the actual sound field in the test vehicle, for a binaural reproduction in the same vehicle, and for a binaural reproduction in a listening room. The results show that the tested binaural reproduction system is able to preserve either the rank order or the perceived magnitudes of the impressions of the sound field for the attributes Precision, Treble, Stereo impression, Bass, and Reverberation, independent of the listening environment.
Convention Paper 8446 (Purchase now)

P20-3 Differences in Preference for Noise Reduction Strength between Individual ListenersRolph Houben, Academic Medical Center - Amsterdam, The Netherlands; Tjeerd M. H. Dijkstra, Radboud University - Nijmegen, The Netherlands; Wouter A. Dreschler, Academic Medical Center - Amsterdam, The Netherlands
There is little research on user preference for different settings of noise reduction, especially for individual users. We therefore measured individual preference for pairs of audio streams differing in noise reduction strength. Data was analyzed with a logistic probability model that is based on a quadratic preference utility function. This allowed for an estimate of the optimal setting for each individual subject. For five out of ten subjects the optimized setting differed significantly from the optimum obtained for the grouped data. However, the predicted preference for the individual optimum (60%) was only slightly higher than chance level (50%), which can be considered as too weak to advocate individualization of noise reduction for these normally hearing subjects. However, in hearing-impaired subjects this may be different.
Convention Paper 8447 (Purchase now)

P20-4 Assessment of Stereo to Surround Upmixers for BroadcastingDavid Marston, BBC R&D - London, UK
Broadcasters are now transmitting 5.1-channel surround sound as part of their HD TV services. However, since much of the audio content in original program material is 2-channel stereo, broadcasters are required to switch between the two formats. Switching between 2- and 5.1-channel formats can cause problems in decoding the content, including switching artifacts and loudness changes. In general it is preferable to transmit all program audio in 5.1 surround, and this can be achieved by automatically upmixing any 2-channel stereo content to 5.1 format prior to broadcasting. This paper reports on tests designed to assess the subjective performance of a selection of upmixers for use in the broadcast chain.
Convention Paper 8448 (Purchase now)

P21 - Processing and Analysis


Monday, May 16, 14:00 — 15:30 (Room: Foyer)

P21-1 Automatic Classification of Musical Audio Signals Employing Machine Learning ApproachPawel Zwan, Bozena Kostek, Adam Kupryjanow, Gdansk University of Technology - Gdansk, Poland
This paper presents a thorough analysis of automatic classification applied to musical audio signals. The classification is based on a chosen set of machine learning algorithms. A database of 60 music composers/performers was prepared for the purpose of the described research. For each of the musicians, 15 to 20 music pieces were collected. All the pieces were partitioned into 20 segments and then parameterized. The feature vector consisted of 171 parameters, including MPEG-7 low-level descriptors and mel-frequency cepstral coefficients (MFCC) complemented with time-related dedicated parameters. The task of the classifier was to recognize the composer/performer and to properly categorize a selected piece of music. The paper also presents and discusses the results of classification.
Convention Paper 8449 (Purchase now)

P21-2 Evaluation of Onset Detection Algorithms in Popular Polyphonic Music on a Large Scale DatabaseStephan Hübler, Rüdiger Hoffmann, Technische Universität Dresden - Dresden Germany
This paper introduces a large database of popular polyphonic music containing drums (10,238 onsets) for the evaluation of onset detection algorithms. The database has been manually annotated by expert listeners. The inter-rater variability leads to an understanding of inter-human variations. Four common detection functions are investigated: spectral difference, high frequency content, phase deviation, and the psychoacoustic one of Klapuri. We present an additional detection function based on the mpeg7 feature audio spectrum envelope. An adaptive peak picker determines the onsets that are compared with the manual labels. Results show that detection functions based on spectral difference obtain observable better results. The study provides a thorough investigation of onset detection algorithms in popular polyphonic music.
Convention Paper 8450 (Purchase now)

P21-3 Using the Viterbi Algorithm for Error Correction in an Autocorrelation-Based Pitch DetectorBob Coover, Gracenote, Inc. - Emeryville, CA, USA
An autocorrelation-based method for detecting the fundamental pitch of an audio signal is presented in which the Viterbi algorithm is used in place of the error correction portion of the detector. The Viterbi algorithm is used to locate the most likely pitch path through the audio file. This method is compared to a typical heuristic and median filtering-based error correction approach that has been historically used in this type of algorithm. The Viterbi algorithm results are significantly better than the typical error correction methods for choosing the best and most plausible path through the pitch estimates.
Convention Paper 8451 (Purchase now)

P21-4 Spectral Equalization for GHA-Applied Restoration to Damaged Historical 78 rpm RecordsTeruo Muraoka, Takahiro Miura, Tohru Ifukube, The University of Tokyo - Tokyo, Japan
The authors have been engaged in the research of In-harmonic Frequency Analysis “GHA,” which enables the separation of desired signal-components and noise. Its primary purpose has been noise-reduction. Recently, the authors succeeded in conducting GHA in practical time length and carried out many sound restorations of historical 78 rpm records. Thanks to GHA’s sufficient separation of target signal-component from noisy objects, the restored signal is noise-less, however its tone quality is unnatural when it is reproduced using current audio equipment. This is due to fact that the recorded sounds were tuned to match to audio equipment in that age, therefore spectral equalization is necessary. In practice, extreme frequency emphases are required, but it had been impossible because of the existences of scratch noise. GHA-applied restoration removed theses difficulties, and equalization curve was obtained by comparing long-term spectrum of restored music with that of the same recorded music by current musicians. Generally equalizations are very complicated and were done utilizing a parametric equalizer.
Convention Paper 8452 (Purchase now)

P21-5 Selection of Approximated Activation Functions in Neural Network-Based Sound Classifiers for Digital Hearing AidsLorena Álvarez, Cosme Llerena, Enrique Alexandre, Roberto Gil-Pita, Manuel Rosa-Zurera, University of Alcalá - Alcalá de Henares, Spain
The feasible implementation of signal processing techniques on hearing aids is constrained by the limited number of instructions per second to implement the algorithms on the digital signal processor the hearing aid is based on. This adversely limits the design of a neural network-based classifier embedded in the hearing aid. Aiming at helping the processor achieve accurate enough results, and in the effort of reducing the number of instructions per second, this paper focuses on exploring the most adequate approximations for the activation function. The experimental work proves that the approximated neural network-based classifier achieves the same efficiency as that reached by the “exact” networks (without these approximations), but, this is the crucial point, with the added advantage of extremely reducing the computational cost on the digital signal processor.
Convention Paper 8453 (Purchase now)

P21-6 Development of Multiband Dynamic Range Compressor Regarding Noise CharacteristicsHoon Heo, Mingu Lee, Seokjin Lee, Koeng-Mo Sung, Seoul National University - Seoul, Korea
It is hard to hear sounds from digital TVs or mobile phones in noisy environments because of the masking effect. It could be solved by a simple amplification; however, special process for masking bands will be a further solution in some restricted situation. We proposed an algorithm named “perceptual irrelevant component elimination” using a modified multiband dynamic range compressor, which does not increase the signal level and enhances its perceptual signal-to-noise ratio by about 1 dB for speech signals and about 3 dB for music signals.
Convention Paper 8454 (Purchase now)

P21-7 Designing Sets of N Doubly Complementary IIR FiltersAlexis Favrot, Christof Faller, Illusonic LLC - Lausanne, Switzerland
A filter design procedure is described for obtaining sets of N doubly complementary IIR filters for any N and any bandpass frequencies. The N doubly complementary IIR filters are built following a tree-like structure based on pairs of doubly complementary IIR filters and additional all-pass filters. The sum of all band signals is an all-pass filtered version of the original audio signal. The complementary IIR filters can be used instead of an analysis filterbank (full rate). The corresponding synthesis filterbank is simply the sum of all band signals. The proposed filters enable high quality delay critical audio processing.
Convention Paper 8455 (Purchase now)


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