AES Barcelona 2005: Paper Session I


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	AES Barcelona 2005 Paper Session I - Multichannel Sound, Part 2 (5.1 Alternatives, WFS)

Last Updated: 20050405, mei

Sunday, May 29, 14:00 — 17:30

Chair: Günther Theile, Institute für Rundfunktechnik - Munich Germany

I-1 Limiting Effects of Active Room Compensation Using Wave Field Synthesis—Sascha Spors, Marcus Renk, Rudolf Rabenstein, University of Erlangen-Nuremberg - Erlangen, Germany
Wave field synthesis (WFS) is an auralization technique that allows control of the wave field within the entire listening area. However, reflections in the listening room interfere with the auralized wave field and may impair the spatial reproduction. Active listening room compensation aims at reducing these impairments by using the WFS system for their compensation. Current realizations of WFS systems are limited to the reproduction in a plane only. This reduction in dimensionality leads to effects that limit the performance of active room compensation. This paper analyzes these limiting effects on a theoretical and practical basis.
Convention Paper 6400 (Purchase now)

I-2 Room Compensation Using Multichannel Inverse Filters for Wave Field Synthesis Systems—Laura Fuster, Jose Javier Lopez, Alberto González, Pedro D. Zuccarello, Universidad Politécnica de Valencia - Valencia, Spain
Wave Field Synthesis is a 3-D audio reproduction system, which allows synthesizing a realistic sound field in an wide area by using arrays of loudspeakers. However, the listening room adds new echoes not considered by the wave field synthesis system, thus deteriorating the spatial effect. This paper proposes a new room compensation approach based on a multichannel inverse filter bank calculated to compensate the room effects at selected points within the listener area. Time domain algorithms are proposed to accurately calculate the bank of inverse filters. Different laboratory experiments have been carried out for validating the method.
Convention Paper 6401 (Purchase now)

I-3 Design and Implementation of a Compatible Wave Field Synthesis Authoring Tool—Sergio Bleda, University of Alicante - Alicante, Spain; José Javier López, Technical University of Valencia - Valencia, Spain; José Escolano, Basilio Pueo, University of Alicante - Alicante, Spain
Wave Field Synthesis (WFS) is a method for spatial sound reproduction, based on the precise construction of the desired wave field by using arrays of loudspeakers. WFS achieves a proper sound rendering for a wide listening area and is one of the most promising 3-D audio systems. However, at present, there are few authoring tools available for sound engineers and the current ones are not very user friendly. To overcome this situation and bring to the audio community a feasible and easy way to start working with WFS systems, the problem is addressed from two different points of view. First, some strategies for the development of an intuitive authoring tool will be presented. Second, a WFS software basis architecture is proposed following the aim of using the least hardware resources possible. This will permit an easy implementation for software developers.
Convention Paper 6402 (Purchase now)

I-4 A Subband Approach to Wave Field Synthesis Rendering—José Javier López, Technical University of Valencia - Valencia, Spain; Sergio Bleda, Basilio Pueo, Jose Escolano, University of Alicante - Alicante, Spain
This paper presents a subband modification of the wave field synthesis rendering algorithm for improving the degradation in the reproduction above the spatial aliasing frequency. With the method presented, the spectrum above the spatial aliasing frequency for each source is reproduced using only one loudspeaker of the array. Several advantages are obtained: there is not any comb-filtering effect, avoids dependence between the spatial aliasing frequency and the cross-over frequency of the transducers such as other methods, and also some computational cost savings. The characteristics of localization cues of the human auditory system at high frequencies help to validate this method psychoacoustically.
Convention Paper 6403 (Purchase now)

I-5 Controlling the Mode Excitation of Rooms by Using Multiple Low Frequency Cardioids in Multichannel Systems—Lampos Ferekidis, R&D Team - Barsinghhausen, Germany; Uwe Kempe, w vier - Lemgo, Germany
Even excitation of room modes is a prerequisite to a balanced, low-frequency transfer characteristic. The spatial distribution of low frequency sources in multichannel systems yields complex mode excitation patterns. The positioning and adjustment of the relative phase of the main speakers to a "single" LFE is addressed in order to achieve a good summation. Finally, large listening areas combined with a well-balanced transfer characteristic are expected in modern multichannel applications. This paper presents solutions by means of using multiple low frequency cardioids to improve the room transfer characteristic. Of particular interest are possible consequences on the decay times of individual modes as well as the signal summation of LFE and main speakers. Further investigations relate to the number of low frequency cardioids and how they relate to the spatial variation of the transfer characteristic in the room.
Convention Paper 6404 (Purchase now)

I-6 Design of a Second-Order Soundfield Microphone—Boaz Rafaely, Ben-Gurion University of the Negev - Beer-Sheva, Israel
A second-order sound-field microphone is desirable for spatial audio recordings and reproduction that use zero, first, and second order harmonics. Recent results in the design and analysis of spherical microphone arrays are employed in this paper to analyze performance of a second-order soundfield microphone configured as a spherical microphone array. The effect of measurement noise, spatial aliasing, microphone positioning accuracy, and microphone response mismatch on performance is evaluated both analytically and using simulations. The analysis presented here can be used to define specifications for a high-quality second-order microphone, and to investigate directions for improving performance.
Convention Paper 6405 (Purchase now)

I-7 The 22.2 Multichannel Sound System and Its Application—Kimio Hamasaki, NHK Science & Technical Research Laboratories, and Kyushu University, Fukuoka, Japan - Tokyo, Japan; Koichiro Hiyama, Reiko Okumura, NHK Science & Technical Research Laboratories - Tokyo, Japan
The 22.2 multichannel sound system was developed for adaptation to an ultrahigh-definition video system with 4000 scanning lines. It consists of three layers of loudspeakers: an upper layer with 9 channels, a middle layer with 10 channels, and a lower layer with 3 channels and 2 channels for LFE (Low Frequency Effects). It can reproduce a greater sensation of presence over a wider listening area compared with conventional multichannel audio systems. This system was first introduced to the public at the World Exposition 2005 in Japan. This paper describes the newest 22.2 multichannel system for the Super Hi-Vision Theater at the World Exposition and discusses advantages of 22.2 multichannel sound. It also describes the sound recordings and productions by 22.2 multichannel sound system.
Convention Paper 6406 (Purchase now)