AES New York 2009
Poster Session P16

P16 - Multichannel Sound and Imaging

Sunday, October 11, 3:30 pm — 5:00 pm
P16-1 Evaluation of a Multipoint Equalization System Based on Impulse Responses Prototype Extraction—Stefania Cecchi, Lorenzo Palestini, Paolo Peretti, Laura Romoli, Francesco Piazza, Università Politecnica delle Marche - Ancona, Italy; Alberto Carini, Universita’ di Urbino - Urbino, Italy
In this paper a frequency domain multipoint equalization algorithm, which combines fractional octave smoothing of measured impulse responses (IRs) in multiple locations and the extraction of a representative prototype, is presented. The proposed approach is evaluated considering different methods to combine the IRs for the prototype extraction and to obtain the inverse filter for equalization, using sets of impulse responses measured in realistic environments. With respect to previous works, the influence on the equalization performance of the number of considered positions and of the equalization zone size is deeply investigated. Also a comparison with the single point equalization approach is reported. Finally, the multipoint equalization robustness is evaluated also on positions different from those used for the equalizer estimation.
Convention Paper 7932 (Purchase now)

P16-2 Acoustic Design of NHK HD-520 Multichannel Postproduction Studio—A New Approach for Room Acoustic Design Using Multi-Layered Random Diffusers—Yasushi Satake, Kazuhiro Makino, Yasuhiro Sakiyama, Hideo Tsuro, Nittobo Acoustic Engineering Co., Ltd. - Tokyo, Japan; Akira Fukada, Ryota Ono, NHK (Japan Broadcasting Corporation) - Shibuya-ku, Tokyo, Japan; Kazutsugu Uchimura, NHK Media Technology - Shibuya-ku, Tokyo, Japan; Junichi Mikami, NHK Integrated Technology - Shibuya-ku, Tokyo, Japan; Masamichi Otani, NHK (Japan Broadcasting Corporation) - Shibuya-ku, Tokyo, Japan; Ikuko Sawaya, NHK Science & Technical Research Laboratories - Ketagaya-ku, Tokyo, Japan
In this paper a novel approach for room acoustic design adopting the renewal project of NHK HD-520 multichannel postproduction studio is introduced. HD-520 studio is designed for direct surround loudspeaker arrangements based on ITU-R BS.775-1 and adopting an acoustically transparent screen. Generally, there are three important keys for acoustic design of multichannel postproduction studios. The first is to obtain stable and flat low frequency responses; the second, smooth panning and accurate phantom sound image. And the third, natural sounds that have well-balanced frequency characteristics. To resolve these problems and produce a superior monitoring environment, a new approach for room acoustic design using multi-layered random diffusers with cylindrical diffusers of different sizes (MLRD) is applied for this project. First of all, an outline and the acoustic design concept for the renewal of NHK HD-520 studio are introduced. Second, the concrete method for room acoustic design for the purpose of certifying the high quality for monitoring of both audio and picture is introduced. The preferable acoustic characteristics were shown in the measurement results, and a high reputation has been given by engineers for the comfortable work area for a surround monitoring environment.
Convention Paper 7933 (Purchase now)

P16-3 Robust Interchannel Correlation (ICC) Estimation Using Constant Interchannel Time Difference (ICTD) Compensation—Dongil Hyun, Yonsei University - Seoul, Korea; Jeongil Seo, Electronics and Telecommunications Research Institute (ETRI) - Daejeon, Korea; Youngcheol Park, Yonsei University - Wonju, Korea; Daehee Youn, Yonsei University - Seoul, Korea
This paper proposes an interchannel correlation (ICC) estimation method that can enhance the performance of the spatial audio coding such as Parametric Stereo of HE-AACv2 and MPEG Surround. Conventional ICC estimation methods assume that phase differences between two channel signals are constant in parameter bands and those phase differences are compensated to maximize the ICC. The proposed method introduces robust ICC estimation by compensating constant interchannel time difference (ICTD). ICTD is estimated from interchannel phase difference (IPD) and linear phases corresponding to ICTD are compensated. ICTD is Simulation results show that the proposed method provides more accurate ICC’s than the conventional methods.
Convention Paper 7934 (Purchase now)

P16-4 Measurement of Audio System Imaging Performance—David Clark, DLC Design - Northville, MI, USA
Mixing engineers assign different sounds to different channels of stereo or multichannel media with the expectation that the listener will experience the intended directional aspects of the sound. For standard +/–30 degree arrangement of playback speakers and listener, this expectation is usually realized. As non-standard influences, such as listening off-centerline, are introduced, localization and other aspects of spatial rendition are degraded. This paper describes a measurement system for quantifying these degradations in common perceptual dimensions such as image direction, width, distance, and stability.
Convention Paper 7936 (Purchase now)

P16-5 Matching Perceived Auditory Width to the Visual Image of a Performing Ensemble in Contrasting Multi-Modal Environments—Daniel L. Valente, Boys Town National Research Hospital - Omaha, NE, USA; Shane A. Myrbeck, Arup Acoustics - San Francisco, CA, USA; Jonas Braasch, Rensselaer Polytechnic Institute - Troy, NY, USA
Participants were given an audio-visual matching test, in which they were instructed to align the acoustic width of a performing ensemble to a varying set of audio and visual cues. Participants are asked to assess a vocal ensemble that is positioned with varying visual width in five contrasting physical spaces with monotonically-increasing Reverberation Times. Each performance to be assessed begins with forced auditory-visual mismatch (the acoustical location of the sound sources not matching that of the visual imagery), and participants were instructed to align the acoustic presentation to the visual imagery of the performance. The results show that the participants' matching ability is based on the source-distance as well as the spacing of the ensemble.
Convention Paper 7937 (Purchase now)

P16-6 Stereo Music Source Separation for 3-D Upmixing—Hwan Shim, Jonathan Abel, Stanford University - Stanford, CA, USA; Koeng-Mo Sung, Seoul National University - Kwanak-Gu, Seoul, Korea
A method for 3-D upmixing based on stereo source separation and a primary-ambient decomposition is presented. The method separately renders primary and ambient components, and separately pans sources derived from the primary signal. Since all separated sources appear in the upmixed output, it is more important that the source separation method be free of audible artifacts than achieve a complete separation of the sources present. Typically, the mixing vector amplitude or energy is allocated to the various sources present, for instance all given to the most likely source, or allocated to each source in proportion to its likelihood. However, these choices produce “musical” noise and source motion artifacts in the upmixed signal. Here, two sources are selected according to the mixing vector direction, and the mixing vector energy is allocated by inverting the panning matrix associated with the selected sources. Listening tests show an upmix with separated sources and few audible artifacts.
Convention Paper 7938 (Purchase now)

P16-7 Automated Assessment of Surround Sound—Richard C. Cabot, Qualis Audio - Lake Oswego, OR, USA
The design of a real time electronic listener, optimized for surround sound program assessment, is described. Problems commonly encountered in surround audio production and distribution are automatically identified, including stereo/mono downmix compatibility, balance, metadata inconsistencies, channel interchange, loudness, excessive or inadequate level, and the presence of hum. Making measurements that correlate with audibility, displaying the results in a form easily understood by non-audio personnel created numerous design challenges. The technology used to solve these challenges, particularly that of downmix compatibility, will be described.
Convention Paper 7939 (Purchase now)