AES London 2010
Recording Industry Event Details
Saturday, May 22, 10:30 — 12:00
(Room C4-Foyer)
P3 - Recording, Production, and Reproduction—Multichannel and Spatial Audio
P3-1 21-Channel Surround System Based on Physical Reconstruction of a Three Dimensional Target Sound Field—Jeongil Seo, Jae-hyoun Yoo, Kyeongok Kang, ETRI - Daejeon, Korea; Filippo M. Fazi, University of Southampton - Southampton, UK
This paper presents the 21-channel sound field reconstruction system based on the physical reconstruction of a three dimensional target sound field over the pre-defined control volume. According to the virtual sound source position and intensity, each loudspeaker signal is estimated through convolving with appropriate FIR filter to reconstruct a target sound field. In addition, the gain of FIR filter is only applied to the mid frequency band of a sound source signal to prevent aliasing effects and to save the computational complexity at the high frequency bands. Also the whole filter processing is carried out at the frequency domain to adopt a real-time application. Through the subjective listening tests the proposed system showed better performance on the localization in the horizontal plane comparing with conventional panning method.
Convention Paper 7973 (Purchase now)
P3-2 Real-Time Implementation of Wave Field Synthesis on NU-Tech Framework Using CUDA Technology—Ariano Lattanzi, Emanuele Ciavattini, Leaff Engineering - Ancona, Italy; Stefania Cecchi, Laura Romoli, Università Politecnica delle Marche - Ancona, Italy; Fabrizio Ferrandi, Politecnico di Milano - Milan, Italy
In this paper we present a novel implementation of a Wave Field Synthesis application based on emerging NVIDIA Compute Unified Device Architecture (CUDA) technology using NU-Tech Framework. CUDA technology unlocks the processing power of the Graphics Processing Units (GPUs) that are characterized by a highly parallel architecture. A wide range of complex algorithms are being re-written in order to benefit from this new approach. Wave Filed Synthesis is a quite new spatial audio rendering technique highly demanding in terms of computational power. We present here results and comparisons between a NU-Tech Plug-In (NUTS) implementing real-time WFS using CUDA libraries and the same algorithm implemented using Intel Integrated Primitives (IPP) Library.
Convention Paper 7974 (Purchase now)
P3-3 Investigation of 3-D Audio Rendering with Parametric Array Loudspeakers—Reuben Johannes, Jia-Wei Beh, Woon-Seng Gan, Ee-Leng Tan, Nanyang Technological University - Singapore
This paper investigates the applicability of parametric array loudspeakers to render 3-D audio. Unlike conventional loudspeakers, parametric array loudspeakers are able to produce sound in a highly directional manner, therefore reducing inter-aural crosstalk and room reflections. The investigation is carried out by performing objective evaluation and comparison between parametric array loudspeakers, conventional loudspeakers, and headphones. The objective evaluation includes crosstalk measurement and binaural cue analysis using a binaural hearing model. Additionally, the paper also investigates how the positioning of the parametric array loudspeakers affects 3-D audio rendering.
Convention Paper 7975 (Purchase now)
P3-4 Robust Representation of Spatial Sound in Stereo-to-Multichannel Upmix—Se-Woon Jeon, Yonsei University - Seoul, Korea; Young-Cheol Park, Yonsei University - Gangwon, Korea; Seok-Pil Lee, Korea Electronics Technology Institute (KETI) - Seoul, Korea; Dae-Hee Youn, Yonsei University - Seoul, Korea
This paper presents a stereo-to-multichannel upmix algorithm based on a source separation method. In the conventional upmix algorithms, panning source and ambient components are decomposed or separated by adaptive algorithm, i.e., least-squares (LS) or least-mean-square (LMS). Separation performance of those algorithms is easily influenced by primary to ambient energy ratio (PAR). Since PAR is time-varying, it causes the energy fluctuation of separated sound sources. To prevent this problem, we propose a robust separation algorithm using a pseudo inverse matrix. And we propose a novel post-scaling algorithm to compensate for the influence of interference with considering desired multichannel format. Performance of the proposed upmix algorithm is confirmed by subjective listening test in ITU 3/2 format.
Convention Paper 7976 (Purchase now)
P3-5 Ambisonic Decoders; Is Historical Hardware the Future?—Andrew J. Horsburgh, D. Fraser Clark, University of the West of Scotland - Paisley, UK
Ambisonic recordings aim to create full sphere audio fields through using a multi-capsule microphone and algorithms based on a “metatheory” as proposed by Gerzon. Until recently, Ambisonic decoding was solely implemented using hardware. Recent advances in computing power now allow for software decoders to supersede hardware units. It is therefore of interest to determine which of the hardware or software decoders provide the most accurate decoding of Ambisonic B-format signals. In this paper we present a comparison between hardware and software decoders with respect to their frequency and phase relationships to determine the most accurate reproduction. Results show that software is able to decode the files with little coloration compared to hardware circuits. It is possible to see which implementation of the analog or digital decoders match the behavioral characteristics of an “ideal” decoder.
Convention Paper 7977 (Purchase now)
P3-6 Localization Curves in Stereo Microphone Techniques—Comparison of Calculations and Listening Tests Results—Magdalena Plewa, Grzegorz Pyda, AGH University of Science and Technology - Kraków, Poland
Stereo microphone techniques are a simple and usable solution to reproduce music scenes while maintaining sound direction maintenance. To choose a proper microphone setup one needs to know the “recording angle” that could be easily determined from localization curves. Localization curves in different stereo microphone techniques can be determined with the use of calculations, which take into consideration interchannel level and time differences. Subjective listening tests were carried out to verify the mentioned calculations. Here we present and discuss the comparison between the calculations and the listening tests.
Convention Paper 7978 (Purchase now)
P3-7 Investigation of Robust Panning Functions for 3-D Loudspeaker Setups—Johann-Markus Batke, Florian Keiler, Technicolor, Research, and Innovation - Hannover Germany
An accurate localization is a key goal for a spatial audio reproduction system. This paper discusses different approaches for audio playback with full spatial information in three dimensions (3-D). Problems of established methods for 3-D audio playback, like the Ambisonics mode matching approach or Vector Base Amplitude Panning (VBAP), are discussed. A new approach is presented with special attention to the treatment of irregular loudspeaker setups, as they are to be expected in real world scenarios like living rooms. This new approach leads to better localization of virtual acoustic sources. Listening tests comparing the new approach with standard mode matching and VBAP will be described in a companion paper.
Convention Paper 7979 (Purchase now)
Saturday, May 22, 11:00 — 12:00 (Saint Julien)
Studio Practices and Production
Abstract:
Technical Committee Meeting on Studio Practices and Production
Saturday, May 22, 14:00 — 16:00 (Room C2)
W2 - AES42 and Digital Microphones
Chair:
Helmut Wittek, SCHOEPS Mikrofone GmbH - Karlsruhe, Germany
Panelists:
Claudio Becker-Foss, DirectOut - Germany
Stephan Flock
Christian Langen
Stephan Peus
Gregor Zielinski, Sennheiser - Germany
Abstract:
The AES42 interface for digital microphones is not yet widely used. This can be due to the relatively new appearance of digital microphone technology, but also a lack of knowledge and practice with digital microphones and the corresponding interface. The advantages and disadvantages have to be communicated in an open and neutral way, regardless of commercial interests, on the basis of the actual need of the engineers.
Along with an available “White paper” about AES42 and digital microphones, which is aimed a neutral in-depth information and was compiled from different authors, the workshop intends to bring to light facts and prejudices on this topic.
Saturday, May 22, 15:30 — 17:00 (Room C1)
T2 - Mastering for Broadcast
Presenter:
Darcy Proper, Galaxy Studios - Belgium
Abstract:
Mastering has often had an aura of mystery around it. Those "in the know" have always regarded it as a vital and necessary last step in the process of producing a record. Those who have never experienced it have often had only a vague idea of what good mastering could achieve. However, the loudness race in recent years has put the mastering community under pressure; on one side from the producers or labels who want their product louder than the competition and on the other side from the artists or mixers who don’t want their work smashed into a lifeless "brick" and maxed out by excessive use of limiter plug-ins.
Darcy Proper is a multi-Grammy-winning mastering engineer whose golden ears (and hands) have put the finishing touches on a vast array of high profile records, among many others those from Steely Dan. She will talk about her approach to her work and will also demo examples with various degrees of compression with a legacy broadcast processor as the final piece of gear in the signal chain, simulating a radio broadcast. The audience is then able to experience the effects and artifacts that different compression levels will cause at the consumer's end.
Saturday, May 22, 16:00 — 18:00 (Room C6)
W3 - Calibration of Analog Reproducing Equipment for Digitization Projects
Chair:
George Brock-Nannestad, Patent Tactics - Denmark
Panelists:
Sean W. Davies, S.W. Davies Ltd. - UK
Andrew Pearson, British Library Sound Archive - UK
Peter Posthumus, Post Sound Ltd.
Abstract:
Analog reproduction equipment sees its last use in the transfer of audio content to digital files. In order to obtain the optimal signal from the carrier (tape and disc) the equipment has to be adjusted. In order to obtain traceability the equipment has to be calibrated. Generations of technicians that did this on a regular basis are vanishing quickly, and making available calibration materials, such as the AES-S001-064 Coarse-groove Calibration disc, is not enough when the know-how for its use is lacking. This workshop aims to redress this situation, in that it provides a firm theoretical underpinning of practical demonstrations, in which the basic principles of calibration and alignment will be discussed along with logging the activity. Keywords are: calibration and alignment of analog tape reproducers, including equipment for tapes that have been encoded, such as Dolby-A and Dolby SR. Furthermore calibration and alignment of gramophone record reproducing equipment will be discussed. Active discussion is encouraged and may spill over into optical sound as found on films.
Sunday, May 23, 09:00 — 11:00 (Room C2)
T3 - Hearing and Hearing Loss Prevention
Presenter:
Benj Kanters, Columbia College - Chicago, IL, USA
Abstract:
The Hearing Conservation Seminar and HearTomorrow.Org are dedicated to promoting awareness of hearing loss and conservation. This program is specifically targeted to students and professionals in the audio and music industries. Experience has shown that engineers and musicians easily understand the concepts of hearing physiology, as many of the principles and theories are the same as those governing audio and acoustics. Moreover, these people are quick to understand the importance of developing their own safe listening habits, as well as being concerned for the hearing health of their clients and the music-listening public. The tutorial is a 2-hour presentation in three sections: first, an introduction to hearing physiology; the second, noise-induced loss; and third, practicing effective and sensible hearing conservation.
Sunday, May 23, 09:00 — 11:00 (Room C1)
W4 - Blu-ray as a High Resolution Audio Format for Stereo and Surround
Chair:
Stefan Bock, msm-studios GmbH - Munich, Germany
Panelists:
Simon Heyworth, SAM - UK
Morten Lindberg, 2L - Norway
Johannes Müller, msm-studios - Germany
Crispin Murray, Metropolis - UK
Ronald Prent, Galaxy Studios - Belgium
Abstract:
The decision for the Blu-ray disc as the only HD packaged media format also offering up to 8 channels of uncompressed high resolution audio has at least eliminated one of the obstacles of getting high-res surround sound music to the market. The concept of utilizing Blu-ray as a pure audio format will be explained, and Blu-ray will be positioned as successor to both SACD and DVD-A. The operational functionality and a double concept of making it usable both with and without screen will be demonstrated by showing a few products that are already on the market.
Sunday, May 23, 11:00 — 13:00 (Room C2)
AES/APRS—Life in the Old Dogs Yet—Part One: Keeping Studios Alive
Moderator:
Andrew Leyshon, Nottingham University
Panelists:
Mark Anders, Bug Music - UK
Malcolm Atkin, formerly AIR and Sphere Studios
Ian Brenchley, MD, Metropolis Studios
Paul Brown, Paul Brown Management
Jonathan Smith, GM, Abbey Road Studios
Abstract:
This Special Event examines the trends in the professional recording business in recent years and invites a new generation of recording entrepreneurs to share ideas often driven by the expanding needs of contemporary clients. Professor Andrew Leyshon from Nottingham University presents his thought-provoking analysis of the changing worldwide recording climate. This is followed by a distinguished panel of recording stakeholders discussing current and possible future recording business models.
Sunday, May 23, 11:30 — 13:00 (Room C1)
T4 - CANCELLED
Sunday, May 23, 13:00 — 14:00 (Saint Julien)
Audio Recording and Mastering Systems
Abstract:
Technical Committee Meeting on Audio Recording and Mastering Systems
Sunday, May 23, 14:00 — 15:45 (Room C2)
W6 - How Do We Evaluate High Resolution Formats for Digital Audio?
Chair:
Hans van Maanen, Temporal Coherence - The Netherlands
Panelists:
Peter Craven
Milind Kunchur, University of South Carolina - SC, USA
Thomas Sporer, Fraunhofer Institue for Digital Media Technology IDMT - Ilmenau, Germany
Menno van der Veen, Ir. Bureau Vanderveen
Wieslaw Woszczyk, McGill University - Montreal, Quebec, Canada
Abstract:
Since the introduction of the High Resolution Formats for Digital Audio (e.g. SACD, 192 kHz / 24 bit), there has been discussion about the audibility of these formats, compared to the CD format (44.1 kHz / 16 bit). What difference does high sample rate and bit depth make in our perception? Can we hear tones above 20 kHz? Can we perceive quantization errors in 16-bit audio? Does high sample rate make a difference in our phase resolution? Are we even asking the right questions? Controlled, scientific listening tests have mostly given ambiguous or inconclusive results, yet a large number of consumers, using "high-end" audio equipment, prefer the sound from the "high resolution" formats over the CD. The workshop will start with introductory notes from the panel members, discussing the differences between "analog" and first-generation digital formats, address some of the paradoxes of the CD format, present results on "circumstantial" evidence and subjective testing, show results on the audibility of the human hearing, which cannot be explained by the commonly accepted 20 kHz upper limit and discuss the problems and pitfalls of "scientific" listening tests, where possible illustrated with demonstrations.
These introductory notes should provoke a discussion with the audience about the audibility of the improvements of the "high resolution" formats We attempt to reach consensus, where possible, regarding what is known and what is not with respect to our ability to perceive the differences between standard and high resolution audio. We further discuss the paradigms of testing for evaluating the quality and perception of high resolution audio, how to structure the tests, how to configure the testing environment, and how to analyze the results.
The outcome of the workshop should also be to find the way forward by identifying the bottlenecks which—at this moment—hamper the further implementation of the "high resolution" formats for "high-end" audio as these formats create an opportunity for the audio industry as a whole: better sources stimulate the development of better reproduction systems.
Sunday, May 23, 16:00 — 19:00 (Room C1)
Recording Competition—Part 1 (World/Folk, Jazz Blues, Pop/Rock)
Abstract:
The Student Recording Competition is a highlight at each convention. A distinguished panel of judges participates in critiquing finalists of each category in an interactive presentation and discussion. This event presents stereo recordings in these categories:
• Jazz/Blues 16:00 to 17:00
• World/Folk 17:00 to 18:00
• Pop/Rock 18:00 to 19:00
The top three finalists in each category present a short summary of their techniques and intentions, and play their projects for all who attend. Meritorious awards will be presented at the closing Student Delegate Assembly Meeting (SDA-2) on Tuesday afternoon.
It’s a great chance to hear the work of your colleagues from other educational institutions. Everyone learns from the judges’ comments even if your project isn’t one of the finalists, and it's a great chance to meet other students and faculty.
Judges include: Stereo – Jazz/Blues: Jim Anderson, Dave McLaughlin, Jim Kaiser. Stereo – World/Folk: Darcy Proper, Andres Mayo, Mark Drews. Stereo – Pop/Rock: Gary Gottlieb, Hugh Robjohns, Barry Marshall.
Monday, May 24, 09:00 — 10:00 (Saint Julien)
High Resolution Audio
Abstract:
Technical Committee Meeting on High Resolution Audio
Monday, May 24, 09:00 — 10:15 (Room C1)
T6 - Classical Music with Perspective
Presenter:
Sabine Maier, Tonmeister - Vienna, Austria
Abstract:
Concerts of classical music, as well as operas, have been a part of broadcast programing since the beginning of television. The aesthetic relationship between sound and picture plays an important part in the satisfactory experience of the consumer. The question how far the audio perspective (if at all!) should follow the video angle (or vice versa) has always been a subject of discussion among sound engineers and producers. In the course of a diploma work this aspect has been investigated systematically. One excerpt of the famous New Year's Concert (from 2009) has been remixed into four distinctly different versions (in stereo and surround sound). Close to 80 laymen who expressed an interest in classical music had the task of judging these versions to the same picture if they found the audio perspective appropriate to the video or not.
In this tutorial the experimental procedure as well as the results will be discussed. Examples of the different mixes will be played.
Monday, May 24, 10:30 — 13:30 (Room C1)
Recording Competition—Part 2 (Stereo Classical, Surround Classical and Non-Classical)
Abstract:
The Student Recording Competition is a highlight at each convention. A distinguished panel of judges participates in critiquing finalists of each category in an interactive presentation and discussion. This event presents stereo and surround recordings in these categories:
• Stereo Classical 10:30 to 11:30
• Surround Classical 11:30 to 12:30
• Surround Non-Classical 12:30 to 13:30
The top three finalists in each category present a short summary of their techniques and intentions, and play their projects for all who attend. Meritorious awards will be presented at the closing Student Delegate Assembly Meeting (SDA-2) on Tuesday afternoon.
It’s a great chance to hear the work of your colleagues from other educational institutions. Everyone learns from the judges’ comments even if your project isn’t one of the finalists, and it's a great chance to meet other students and faculty.
Judges include: Stereo – Classical: Tony Falkner, Ken Blair, David Bowles. Surround – Classical: Philip Hobbs, Tin Jonker, Bastian Kuijit. Surround – Non-Classical: Ron Prent, Thor Legvold, Bill Crabtree.
Monday, May 24, 14:00 — 15:45 (Room C2)
T8 - Les Paul: We Use His Innovations Every Day
Presenter:
Barry Marshall
Abstract:
The many contributions of the late Les Paul to the art and technology of recording were often overlooked in media coverage of his passing last year at the age of 94. While his importance as a musician and as an innovator of the solid body electric guitar certainly deserve wide praise and respect, his developments in recording continue to be used by producers, engineers and musicians at virtually every recording session. Producer and educator Barry Marshall looks at the career of Les Paul and plays some of his ground-breaking recordings as a sideman, as a solo artist, and as a part of the Les Paul and Mary Ford duo act. Special emphasis in the presentation will be placed on the way that Les' musicianship and musical instincts drove his technical breakthroughs.
Monday, May 24, 16:00 — 18:00 (Room C1)
Education Forum Panel
Moderator:
Gary Gottlieb
Presenters:
Chuck Ainlay
Akira Fukada
George Massenburg
Ulrike Schwarz
Abstract:
How Does It Sound Now, the Evolution of Audio
One day Chet Atkins was playing guitar when a woman approached him. She said, “That guitar sounds beautiful.” Chet immediately quit playing. Staring her in the eyes he asked, “How does it sound now?” The quality of the sound in Chet’s case clearly rested with the player, not the instrument, and the quality of our product ultimately lies with us as engineers and producers, not with the gear we use. The dual significance of this question, “How does it sound now,” informs our discussion, since it addresses both the engineer as the driver and the changes we have seen and heard as our business and methodology have evolved through the decades. Let’s start by exploring the methodology employed by the most successful among us when confronted with new and evolving technology. How do we retain quality and continue to create a product that conforms to our own high standards? Is this even possible for students in today’s market, with the option of true apprenticeships all but gone? How can students develop chops, aesthetics, and technical knowledge? How can they become prepared to thrive and produce a quality product? Can we help give educators the tools they need to address the issue of continuity of quality? This may lead to other conversations about the musicians we work with, the consumers we serve, and the differences and similarities between their standards and our own. How high should your standards be? How should it sound now? How should it sound tomorrow?
Tuesday, May 25, 09:00 — 10:45 (Room C2)
T9 - Compression FX—Use Your Power for Good, Not Evil
Presenter:
Alex U. Case, University of Massachusetts Lowell - Lowell, MA, USA
Abstract:
Dynamic range compression, so often avoided by the purist and damned by the press, is most enthusiastically embraced by pop music creators. As an audio effect, it can be easily overused. Reined-in it can be difficult to perceive. It is always difficult to describe. As a tool, its controls can be counterintuitive, and its meters and flashing lights uninformative. In this tutorial—rich with audio examples—Case organizes the broad range of iconic effects created by audio compressors as they are used it to reduce and control dynamic range, increase perceived loudness, improve intelligibility and articulation, reshape the amplitude envelope, add creative doses of distortion, and extract ambience cues, breaths, squeaks, and rattles. Learn when pop engineers reach for compression, know what sort of parameter settings are used (ratio, threshold, attack, and release), and advance your understanding of what to listen for and which way to tweak.
Tuesday, May 25, 09:00 — 10:45 (Room C1)
W15 - Single-Unit Surround Microphones
Chair:
Eddy B. Brixen, EBB-Consult - Smørum, Denmark
Panelists:
Mikkel Nymand, DPA Microphones
Mattias Strömberg, Milab - Helsingborg, Sweden
Helmut Wittek, SCHOEPS Mikrofone GmbH
Abstract:
The workshop will present available single-unit surround sound microphones in a kind of shoot out. There are a number of these microphones available and more units are on their way. These microphones are based on different principles. However, due to their compact sizes there may/may not be restrictions to the performance. This workshop will present the different products and the ideas and theories behind them.
Tuesday, May 25, 14:00 — 15:45 (Room C2)
AES/APRS—Life in the Old Dogs Yet—Part Three: After the Ball—Protecting the Crown Jewels
Moderator:
John Spencer, BMS CHACE
Panelists:
Chris Clark, British Library Sound Archive
Tommy D, Producer
Tony Dunne, A&R Coordinator, DECCA Records and UMTV/UMR - UK
Simon Hutchinson, PPL
Paul Jessop, Consulant IFI/RIAA
George Massenburg, P&E Wing, NARAS
Abstract:
A fascinating peek into the unspoken worlds of archiving and asset protection. It examines the issues surrounding retrievable formats that promise to future-proof recorded assets and the increasing importance of accurate recordings information (metadata). A unique group of experts from archiving and royalty distribution communities will hear a presentation from John Spencer, from BMS CHACE in Nashville, explaining his work with NARAS and the U.S. Library of Congress to establish an information schema for sound recording and Film and TV audio and then engage in a group discussion. The discussion then moves onto probably the most important topic to impact on the future of the sound and music economies—how to keep what we’ve got and reward those who made it.
Sir George Martin CBE was also awarded an AES Honorary Membership just before this session started. The award was introduced by AES Past President Jim Anderson and presented to Sir George by AES President Diemer de Vries. Click here to watch a video of the presentation.
Tuesday, May 25, 14:00 — 15:30 (Room C4-Foyer)
P26 - Recording, Production, and Reproduction—Multichannel and Spatial Audio
P26-1 Evaluation of Virtual Source Localization Using 3-D Loudspeaker Setups—Florian Keiler, Johann-Markus Batke, Technicolor, Research, and Innovation - Hannover Germany
This paper evaluates the localization accuracy of different playback methods for 3-D spatial sound using a listening test. The playback methods are characterized by their panning functions that define the gain for each loudspeaker to play back a sound source positioned at a distinct pair of azimuth and elevation angles. The tested methods are Ambisonics decoding using the mode matching approach, vector base amplitude panning (VBAP), and a newly proposed 3-D robust panning approach. For irregular 3-D loudspeaker setups, as found in home environments, the mode matching shows poor localization. The new 3-D robust panning leads to a better localization and can also outperform the VBAP technology dependent on the source position and the loudspeaker setup used.
Convention Paper 8060 (Purchase now)
P26-2 Optimization of the Localization Performance of Irregular Ambisonic Decoders for Multiple Off-Center Listeners—David Moore, Glasgow Caledonian University - Glasgow, Lanarkshire, UK; Jonathan Wakefield, University of Huddersfield - Huddersfield, West Yorkshire, UK
This paper presents a method for optimizing the performance of irregular Ambisonic decoders for multiple off-center listeners. New off-center evaluation criteria are added to a multi-objective fitness function, based on auditory localization theory, which guides a heuristic search algorithm to derive decoder parameter sets for the ITU 5-speaker layout. The new evaluation criteria are based upon Gerzon’s Metatheory of Auditory Localization and have been modified to take into account off-center listening positions. The derived decoders exhibit improved theoretical localization performance for off-center listeners. The theoretical results are supported by initial listening test results.
Convention Paper 8061 (Purchase now)
P26-3 Vibrational Behavior of High Aspect Ratio Multiactuator Panels—Basilio Pueo, Jorge A. López, Javier Moralejo, University of Alicante - Alicante, Spain; José Javier López, Technical University of Valencia - Valencia, Spain
Multiactuator Panels (MAPs) consist of a flat panel of a light and stiff material to which a number of mechanical exciters are attached, creating bending waves that are then radiated as sound fields. MAPs can substitute the traditional dynamic loudspeaker arrays for Wave Field Synthesis (WFS) with added benefits, such as the low visual profile or omnidirectional radiation. However, the exciter interaction with the panel, the panel material, and the panel edge boundary conditions are some of the critical points that need to be evaluated and improved. In this paper the structural acoustic behavior of a high aspect ratio MAP is analyzed for two classical edge boundary conditions: free and clamped. For that purpose, the surface velocity over the whole area of the MAP prototype has been measured with a Laser Doppler Vibrometer (LDV), which helped in understanding the sound-generating behavior of the panel.
Convention Paper 8062 (Purchase now)
P26-4 Design of a Circular Microphone Array for Panoramic Audio Recording and Reproduction: Microphone Directivity—Hüseyin Hacihabiboglu, Enzo De Sena, Zoran Cvetkovic, King's College London - London, UK
Design of a circularly symmetric multichannel recording and reproduction system is discussed in this paper. The system consists of an array of directional microphones evenly distributed on a circle and a matching array of loudspeakers. The relation between the microphone directivity and the radius of the circular array is established within the context of time-intensity stereophony. The microphone directivity design is identified as a constrained linear least squares optimization problem. Results of a subjective evaluation are presented that indicate the usefulness of the proposed microphone array design technique.
Convention Paper 8063 (Purchase now)
P26-5 Design of a Circular Microphone Array for Panoramic Audio Recording and Reproduction: Array Radius—Enzo De Sena, Hüseyin Hacihabiboglu, Zoran Cvetkovic, King's College London - London, UK
A multichannel audio system proposed by Johnston and Lam aims at perceptual reconstruction of the sound field of an acoustic performance in its original venue. The system employs a circular microphone array, of 31 cm diameter, to capture relevant spatial cues. This design proved to be effective in the rendition of the auditory perspective, however other studies showed that there is still substantial room for improvement. This paper investigates the impact of the array diameter on the width and naturalness of the auditory images. To this end we propose a method for quantification and prediction of the perceived naturalness. Simulation results support array diameters close to that proposed by Johnston and Lam in the sense that they achieve optimal naturalness in the center of the listening area, but also suggest that larger arrays might provide a more graceful degradation of the naturalness for listening positions away from the center.
Convention Paper 8064 (Purchase now)
P26-6 MIAUDIO—Audio Mixture Digital Matrix—David Pedrosa Branco, José Neto Vieira, Iouliia Skliarova, Universidade de Aveiro - Aveiro, Portugal
Electroacoustic music is turning more and more to the sound diffusion techniques. Multichannel sound systems like BEAST and SARC are built so that the musician can independently control the intensity of several audio channels. This feature provides the possibility of creating several sound diffusion scenarios, i.e., immersion and the possibility of movement around the audience. The developed system (MIAUDIO) is a real-time sound diffusion system currently able to mix up to 8 audio input channels through 32 output channels. A hardware solution was adopted using a Field Programmable Gate Array (FPGA) to perform the mixture. The analog audio signals are conditioned, converted to digital format by several analog-to-digital converters, and then sent to the FPGA that is responsible to perform the mixing algorithm. The host computer connects to the FPGA via USB and is responsible for supplying the parameters that define the audio mixture. Being so, the user has control over the input levels through the output channels independently. MIAUDIO was successfully implemented with a low-cost solution when compared with similar systems. All the channels were tested using a Precision One system with very good results.
Convention Paper 8065 (Purchase now)
P26-7 The Perception of Focused Sources in Wave Field Synthesis as a Function of Listener Angle—Robert Oldfield, Ian Drumm, Jos Hirst, University of Salford - Salford, UK
Wave field synthesis (WFS) is a volumetric sound reproduction technique that allows virtual sources to be positioned anywhere in space. The reproduction of the wave field of these sources means they can be accurately localized even when placed in front of the secondary sources/loudspeakers. Such “focused sources” are very important in WFS as they greatly add to the realism of an auditory scene, however the perception and localization-ability changes with listener and virtual source position. In this paper we present subjective tests to determine the localization accuracy as a function of angle, defining the subjective “view angle.” We also show how improvements can be made through the addition of the first order image sources.
Convention Paper 8066 (Purchase now)
P26-8 Gram-Schmidt-Based Downmixer and Decorrelator in the MPEG Surround Coding—Der-Pei Chen, Hsu-Feng Hsiao, Han-Wen Hsu, Chi-Min Liu, National Chiao Tung University - Hsinchu, Taiwan
MPEG Surround (MPS) coding is an efficient method for multichannel audio coding. In MPS coding, downmixing from multichannel signals into a fewer number of channels is an efficient way to achieve a high compression rate in an encoder. In decoder, an upmixing module combining with the decorrelator is the key module to reconstruct the multichannel signals. This paper considers the design of the downmixer and the decorrelator through the Gram-Schmidt orthogonal process. The individual and joint effects from the downmixer and decorrelator are verified through intensive subjective and objective quality measure.
Convention Paper 8067 (Purchase now)
