AES London 2011
Paper Session P12

P12 - Binaural Sound

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

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)

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