AES San Francisco 2012
Engineering Brief Details

EB1 - eBrief Presentations—Posters 1

Saturday, October 27, 10:00 am — 11:30 am (Foyer)

EB1-1 Accuracy of ITU-R BS.1770 Algorithm in Evaluating Multitrack MaterialPedro Duarte Pestana, CITAR-UCP - Almada, Portugal; CEAUL-FCUL; Alvaro Barbosa, Universidade Lisboa - Lisbon, Portugal
Loudness measurement that is computationally efficient and applicable on digital material disregarding listening level is a very important feature for automatic mixing. Recent work in broadcast specifications of loudness (ITU-R BS.1770) deserved broad acceptance and seems a likely candidate for extension to multitrack material, though the original design did not bear in mind this kind of development. Some empirical observations have suggested that certain types of individual source materials are not evaluated properly by the ITU’s algorithm. In this paper a subjective test is presented that tries to shed some light on the subject.
Engineering Brief 53 (Download now)

EB1-2 An Online Resource for the Subjective Comparison of Vocal MicrophonesBradford Swanson, University of Massachusetts - Lowell - Lowell, MA, USA
Forty-eight microphones were gathered into small groups and tested using four vocalists (two male, two female). The recorded results are collected online so users may subjectively compare a single performance on closely related microphones.
Engineering Brief 54 (Download now)

EB1-3 Perception of Distance and the Effect on Sound Recording Distance Suitability for a 3-D or 2-D ImageLuiz Fernando Kruszielski, Tokyo University of the Arts - Adachi-ku, Tokyo, Japan; Toru Kamekawa, Tokyo University of the Arts - Tokyo, Japan; Atsushi Marui, Tokyo University of the Arts - Adachi-ku, Tokyo, Japan
Possible differences in the perception of the sound caused by 3-D image are still unclear. The aim of this research is to understand a possible difference in the perception of distance caused by interaction of sound and 3-D image compared to a 2-D image and also how this could affect the suitability of the sound recording distance. Using a 3-D setup, a saxophone player was recorded at five different distances. The subjects where asked to judge their subjective distance and also the suitable sound for the presented image. The results show that one group perceived 3-D to be more distant, however it did not change the sound suitability compared 3-D to 2-D.
Engineering Brief 55 (Download now)

EB1-4 Modeling Auditory-Haptic Interface Cues from an Analog Multi-line TelephoneDurand Begault, Human Systems Integration Division, NASA Ames Research Center - Moffett Field, CA, USA; Mark R. Anderson, Dell Systems, NASA Ames Research Center - Moffett Field, CA, USA; Rachel M. Bittner, New York University - New York, NY, USA
The Western Electric company produced influential multi-line telephone designs during the 1940s–1970s using a six-button interface (line selection, hold button, intercom). Its simplicity was an example of a successful human factors design. Unlike touchscreen or membrane switches used in its modern equivalents, the older multi-line telephone used raised surface mechanical buttons that provided robust tactile, haptic, and auditory cues. This multi-line telephone was used as a model for a trade study comparison of two interfaces: a touchscreen interface (iPad) versus a pressure-sensitive strain gauge button interface (Phidget USB interface controllers). This engineering brief describes how the interface logic and the visual and auditory cues of the original telephone were analyzed and then synthesized using MAX-MSP. (The experiment and results are detailed in the authors' AES 133rd convention paper "Multimodal Information Management: Evaluation of Auditory and Haptic Cues for NextGen Communication Displays").
Engineering Brief 56 (Download now)

EB1-5 Tailoring Practice Room Acoustics to Student NeedsScott R. Burgess, Central Michigan University - Mt. Pleasant, MI, USA
A crucial part of any music education facility is the student practice rooms. While these rooms typically vary in size, the acoustic treatments often take a "one size fits all" approach. This can lead to student dissatisfaction and a lack of rooms that are suitable to some instruments. The School of Music at Central Michigan University surveyed our students and created a variety of acoustic environments based on the results of this survey. This presentation will discuss this process and the results of the follow-up survey, which indicates an improvement in student satisfaction, along with suggestions for further study.
Engineering Brief 57 (Download now)

EB1-6 Acoustic Properties of Small Practice Rooms Where Musicians Can Practice Contentedly: Effect of Reverberation on PracticeRitsuko Tsuchikura, SONA Corp. - Nakano-ku, Tokyo, Japan; Masataka Nakahara, ONFUTURE Ltd. - Tokyo, Japan; SONA Corp. - Tokyo, Japan; Takashi Mikami, SONA Co. - Tokyo, Japan; Toru Kamekawa, Tokyo University of the Arts - Tokyo, Japan; Atsushi Marui, Tokyo University of the Arts - Adachi-ku, Tokyo, Japan
This paper describes results of study on practice room acoustics regarding the level of satisfaction players feel about the acoustical conditions. Two different factors are found to be involved for musicians to evaluate the acoustics of practice rooms: "comfort in practice" and "comfort in performance." Further evaluation of the two factors shows that "comfort in practice" and "comfort in performance" have different desired reverberation times. The average absorption coefficients, therefore, are estimated. Though the experiments were carried out on several kinds of instruments, this paper describes the results of experiments involving trumpeters and violinists.
Engineering Brief 58 (Download now)

EB1-7 Bellamy Baffle Array: A Multichannel Recording Technique to Improve Listener EnvelopmentSteven Bellamy, Humber College - Toronto, ON, Canada
The paper outlines a 6-microphone technique that makes use of a baffle between front and rear arrays. This addresses three common challenges in multichannel recording for 5.1 channel playback. First, to improve the sense of connectedness between LS/RS, L/LS and R/RS channel pairs. Second, to maintain clarity of the direct sound while allowing for strong levels of room sound in the mix. Third, to provide a flexible system that can work well with a variety of ensembles. The result is a flexible microphone technique that results in recordings of increased clarity and envelopment.
Engineering Brief 59 (Download now)


EB2 - eBrief Presentations—Lectures 1

Sunday, October 28, 4:00 pm — 5:45 pm (Room 122)

Lance Reichert, Sennheiser Electronic Corporation - San Francisco, CA, USA

EB2-1 A Comparison of Highly Configurable CPU- and GPU-Based Convolution EnginesMichael Schoeffler, International Audio Laboratories Erlangen - Erlangen, Germany; Wolfgang Hess, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
In this work the performance of real-time audio signal processing convolution engines is evaluated. A CPU-based implementation using the Integrated Performance Primitives Library and two GPU-based implementations using CUDA and OpenCL are compared. The purpose of these convolution engines is auralization, e.g., the binaural rendering of virtual multichannel configurations. Any multichannel input and output configuration is supported, e.g., 22.2 to 5.1, 7.1 to 2.0, vice versa, etc. This ability results in a trade-off between configurability and performance. Using a 5.1-to-binaural setup with continuous filter changes due to simulated head-tracking, GPU processing is more efficient when 24 filters of more than 1.92 seconds duration each @ 48 kHz sampling rate are convolved. The GPU is capable of convolving longer filters in real-time than a CPU-based processing. By comparing both GPU-based implementations, negligible performance differences between OpenCL and CUDA were measured.
Engineering Brief 60 (Download now)

EB2-2 Multichannel Audio Processor which Adapts to 2-D and 3-D Loudspeaker SetupsChristof Faller, Illusonic - Uster, Switzerland
A general audio format conversion concept is described for reproducing stereo and surround audio content on loudspeaker setups with any number of channels. The goal is to improve localization and to generate a recording-related spatial impression of depth and immersion. It is explained how with these goals signals are processed using a strategy that is independent of a specific loudspeaker setup. The implementation of this general audio format conversion concept, in the Illusonic Immersive Audio Processor, is described.
Engineering Brief 61 (Download now)

EB2-3 A Comparison of Recording, Rendering, and Reproduction Techniques for Multichannel Spatial AudioDavid Romblom, McGill University - Montreal, Quebec, Canada; Catherine Guastavino, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada; Richard King, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada
The objective of this project is to compare the relative merits of two different spatial audio recording and rendering techniques within the context of two different multichannel reproduction systems. The two recordings and rendering techniques are "natural," using main microphone arrays, and "virtual," using spot microphones, panning, and simulated acoustic delay. The two reproduction systems are the 3/2 system (5.1 surround), and a 12/2 system, where the frontal L/C/R triplet is replaced by a 12 loudspeaker linear array. Additionally, the project seeks to know if standard surround techniques can be used in combination with wavefront reconstruction techniques such as Wave Field Synthesis. The Hamasaki Square was used for the room effect in all cases, exhibiting the startling quality of increasing the depth of the frontal image.
Engineering Brief 62 (Download now)

EB2-4 The Reactive Source: A Reproduction Format Agnostic and Adaptive Spatial Audio EffectFrank Melchior, BBC R&D - Salford, UK
Spatial audio has become a more and more active field of research and various systems are currently under investigation on different scales of effort and complexity. Given the potential of 3-D audio systems, spatial effects beyond source positioning and room simulation are desirable to enhance the creative flexibility. This paper describes a new adaptive spatial audio effect called reactive source. The reactive source uses low-level features of the incoming audio signal to dynamically adapt the spatial behavior of a sound source. Furthermore, the concept is format agnostic so that the effect could easily be applied to different 3-D audio reproduction methods using the same interaction method. To verify the basic concept, a prototype system for multichannel reproduction has been developed.
Engineering Brief 63 (Download now)

EB2-5 Teaching Critical Thinking in an Audio Production CurriculumJason Corey, University of Michigan - Ann Arbor, MI, USA
The practice of sound recording and production can be characterized as a series of decisions based primarily on subjective impressions of sound. These subjective impressions lead to equipment choices and use, not only for artistic effect but also to accomplish technical objectives. Nonetheless, the ability to think critically about recording techniques, equipment specifications, and sound quality is vitally important to equipment choice and use. The goal of this paper is to propose methods to encourage critical thinking among students in an audio production curriculum and to consider topics that might be included in coursework to help aspiring audio engineers evaluate audio equipment and processing.
Engineering Brief 64 (Download now)

EB2-6 Sync-AV – Workflow Tool for File-Based Video ShootingsAndreas Fitza, University of Applied Science Mainz - Mainz, Germany
The Sync-AV workflow eases the sorting and synchronization of video and audio footage without the needs of expensive special hardware. It supports the preproduction and the shooting as well as the post-production. It consists of three elements: A script-information- and metadata-gathering iOS app that is synchronized with a server-back-end. It can be used on different devices at once to exchange information onset. A server database with a web-front-end that can sort files by their metadata and show dailies as well. It can also be used to distribute and manage information during the preproduction. A local client that can synchronize and rename the files and that implements the metadata.
Engineering Brief 65 (Download now)

EB2-7 Audio over IP Kieran Walsh, Audinate Pty. Ltd. - Ultimo, NSW, Australia
Developments in both IP networking and the attitude of professional audio to emerging technologies have presented the opportunity to consider a more abstract and all-encompassing approach to the ways that we manage data. We will examine this paradigm shift and discuss the benefits presented both in practical terms and creatively.
Engineering Brief 66 (Download now)


EB3 - eBrief Presentations—Posters 2

Monday, October 29, 9:30 am — 11:00 am (Foyer)

EB3-1 Implementation of an Interactive 3-D Reverberator for Video Games Using Statistical AcousticsMasataka Nakahara, ONFUTURE Ltd. - Tokyo, Japan; SONA Corp. - Tokyo, Japan; Tomoya Kishi, CAPCOM Co., Ltd. - Okaka-shi, Oasaka-fu, Japan; Kenji Kojima, CAPCOM Co. Ltd.; Toshiki Hanyu, Nihon University - Funabashi, Chiba, Japan; Kazuma Hoshi, Nihon University - Chiba-ken, Japan
An interactive reverberator, which applies realistic computed acoustic responses interactively to video game scenes, is a very important technology for the processing of in-game sounds. The mainframe of an interactive reverberator, which the authors developed, is designed based on statistical acoustics theory, so that it is possible to compute fast enough to realize real-time processing in fast-changing game scenes. Though statistical reverbs generally do not provide a high level of reality, the authors have achieved a quantum leap of sound quality by applying Hanyu's algorithm to conventional theories. The reverberator features: (1) No pre-computing jobs including room modeling are required. (2) Three-dimensional responses are generated automatically. (3) Complex factor of a room's shape, open-air areas, and effects of neighboring reverberations are expressed. The authors implemented the reverberator into a Capcom’s middleware experimentally and have verified it can run effectively. In this paper the algorithm, background theories, and implementation techniques are introduced.
Engineering Brief 67 (Download now)

EB3-2 Printable Loudspeaker Arrays for Flexible Substrates and Interactive SurfacesJess Rowland, University of California, Berkeley - Berkeley, CA, USA; Adrian Freed, University of California, Berkeley - Berkeley, CA, USA
Although planar loudspeaker drivers have been well explored for many years, a flat speaker array system that may flex or fold freely remains a current challenge to engineer. We will demonstrate a viable technique for building large loudspeaker arrays that allow for diffused fields of sound transduction on flexible membranes. Planar voice coils are made from machine-cut copper sheets, or by inkjet printing and electroless copper plating, on paper, thin plastic, or similar lightweight material. We will present various ways of attaching thin magnets to these membranes, including a novel alternative strategy of mounting magnets in gloves worn by the listener. This creates an engaging experience for listeners in which gestures can control sounds from the speaker array interactively.
Engineering Brief 68 (Download now)

EB3-3 Nonlinear Distortion Measurement in Audio Amplifiers: The Perceptual Nonlinear Distortion ResponsePhillip Minnick, University of Miami - Coral Gables, FL, USA
A new metric for measuring nonlinear distortion is introduced called the Perceptual Nonlinear Distortion Response (PNDR) to measure nonlinear distortion in audio amplifiers. This metric accounts for the auditory system's masking effects. Salient features of previously developed nonlinear distortion measurements are considered in the development of the PNDR. A small group of solid-state and valve audio amplifiers were subjected to various benchmark tests. A listening test was created to test perceptibility of nonlinear distortions generated in the amplifiers. These test results were analyzed and the Perceptual Nonlinear Distortion Response was more successful than traditionally used distortion metrics. This cognitive tool could provide the audio industry with more accurate test methods, facilitating product research and development.
Engineering Brief 69 (Download now)

EB3-4 EspGrid: A Protocol for Participatory Electronic Ensemble PerformanceDavid Ogborn, McMaster University - Hamilton, ON, Canada
EspGrid is a protocol developed to streamline the sharing of timing, code, audio, and video in participatory electronic ensembles, such as laptop orchestras. An application implementing the protocol runs on every machine in the ensemble, and a series of “thin” helper objects connect the shared data to the diverse languages that live electronic musicians use during performance (Max, ChucK, SuperCollider, PD, etc.). The protocol/application has been developed and tested in the busy rehearsal and performance environment of McMaster University’s Cybernetic Orchestra, during the project “Scalable, Collective Traditions of Electronic Sound Performance” supported by Canada’s Social Sciences and Humanities Research Council (SSHRC), and the Arts Research Board of McMaster University.
Engineering Brief 70 (Download now)

EB3-5 A Microphone Technique for Improved Stereo Image, Spatial Realism, and Mixing Flexibility: STAGG (Stereo Technique for Augmented Ambience Gradient)Jamie Tagg, McGill University - Montreal, Quebec, Canada
While working on location, recording engineers are often challenged by insufficient monitoring. Poor (temporary control room) acoustics or headphone monitoring can make judgments regarding microphone choice and placement difficult. These choices often lead to timbral, phase, and stereo image problems. We are often forced to choose between the improved spatial imaging of near-coincident techniques and the acoustic envelopment from spaced omni-directional mics. This poster proposes a new technique: STAAG (Stereo Technique for Augmented Ambience Gradient), which aims to improve stereo image, acoustic realism, and flexibility in the mix. The STAAG technique allows for adjustment of the acoustic envelopment once in a proper monitoring environment.
Engineering Brief 71 (Download now)


EB4 - eBrief Presentations—Lectures 2

Monday, October 29, 2:00 pm — 3:15 pm (Room 121)

Tad Rollow

EB4-1 Parametric Horn DesignAmbrose Thompson, Martin Audio - High Wycombe, UK
The principle barrier to more widespread use of numerical techniques for horn design is not a shortage of advanced computational libraries, rather the difficultly in defining the problem to solve in a suitable format. The traditional approach of creating horn geometry in large commercial CAD programs then exporting, meshing, assigning conditions, solving, and inspecting results denies the engineer the ability to easily iterate the design. We introduce an object-orientated parametric description of a horn that enables the engineer to modify meaningful parameters to generate geometry of appropriate complexity. The entire process is performed in one environment and an early implementation has been shown to allow nearly 100 iterations of one horn in one week. Results for this and another multi-driver HF horn are given.
Engineering Brief 72 (Download now)

EB4-2 Integration of Touch Pressure and Position Sensing with Speaker DiaphragmsAdrian Freed, University of California, Berkeley - Berkeley, CA, USA
Speaker cones and other driver diaphragms are usually too fragile to be good sites for touch interaction. This can be solved by employing new, lightweight piezoresistive e-textiles with flat, rectangular, stiff surfaces used in full-range drivers from HiWave. Good low-frequency performance of piezoresistive fabric has an advantage over piezoelectric sensing for this situation. Applications of these integrated sensor/actuators include haptic feedback user interfaces and responsive electronic percussion instruments.
Engineering Brief 73 (Download now)

EB4-3 Power Entry—Where High Performance Design BeginsChristopher Peters, Schurter - Santa Rosa, CA, USA; Diane Cupples, Schurter, Inc. - Santa Rosa, CA, USA
What is EMC/EMI? Where does it come from? What steps do I need to take to insure compatibility in today's world? Power quality as it relates to electro-magnetic compatibility is a growing topic among audio equipment manufacturers in the advent of the digital age. This abstract looks at equipment emissions and susceptibility and how to remedy noise problems with effective EMC design in the early stages. The paper and presentation will also offer ideas for integrating voltage selection, overcurrent protection and on/off switching into the overall aspects of compact, high performance design. Cord connection and retaining systems will also be covered.
Engineering Brief 74 (Download now)

EB4-4 Design and Construction of the Tri-Baffle: A Modular Acoustic Modification System for Task-Based Mixing ExperimentsScott Levine, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada; Brett Leonard, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada; Richard King, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada
The Tri-Baffle is a modular system capable of providing multiple acoustic conditions within a space through the use of absorptive, reflective, and diffusive materials. Each baffle is constructed in a triangular frame, and capable of rotation via a ground-positioned motor. The system was designed and constructed to fit multiple experimental requirements such as acoustic characteristics, time requirements, installation concerns, and portability. As constructed, the Tri-Baffle is fully portable and is capable of installation in any space where task-based experimentation is desired.
Engineering Brief 75 (Download now)

EB4-5 Another View of Distortion PerceptionJohn Vanderkooy, University of Waterloo - Waterloo, ON, Canada; Kevin B. Krauel, University of Waterloo - Waterloo, ON, Canada
Perception of distortion is difficult to determine since it relies critically on signal level. We study a distortion characteristic possessing a relative distortion independent of signal level—a simple change in slope between positive and negative signal excursion. A mathematical analysis is presented, showing the resulting distortion to be mainly even harmonic but with some rectification effects, which need consideration. Various signals are evaluated by informal A/B listening tests, including pure tones and music. Judiciously-chosen signals have distortions that are detectable only if they are above 1%, in keeping with psychoacoustic masking data, while real music signals are considerably more tolerant of distortion up to levels of 5% or more! This implies that, except for crossover distortion, present-day electronic systems are all sufficiently linear.
Engineering Brief 76 (Download now)

EB4-6 How Can Sample Rates Be Properly Compared in Terms of Audio Quality?Richard King, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada; Daniel Levitin, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada; Brett Leonard, McGill University - Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology - Montreal, Quebec, Canada
A listening test was designed to compare audio quality using varying sample rates. A Yamaha Disklavier player piano was used as a repeatable acoustic source, and the signal from the microphone preamps was sent to three identical analog to digital converters of the same make and model. The digitized signals were then re-converted to analog and compared to the original "live" signal through the use of a four-way switcher. Sample rates were 44.1, 96, and 192 kHz. Technical setup and the "somewhat inconclusive" results are discussed, along with some possible options for future testing.
Engineering Brief 77 (Download now)


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AES - Audio Engineering Society