AES London 2011
Poster Session P17

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)

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