AES Vienna 2007: Paper Session P11

P11 - Multichannel Sound - 2

Sunday, May 6, 12:30 — 15:30

Chair: Ulrike Schwarz

P11-1 EBU Tests of Multichannel Audio Codecs—Andrew Mason, David Marston, British Broadcasting Corporation - Tasworth, Surrey, UK; Franc Kozamernik, EBU - Geneva, Switzerland; Gerhard Stoll, IRT - Munich, Germany
The latest project of one of the European Broadcasting Union technical groups has been the assessment of the sound quality of multichannel audio bit rate reduction codecs for broadcast applications. Codecs under test include offerings from Dolby, DTS, implementations of MPEG AAC, and of the new MPEG Surround codec. The bit rates ranged from 64 kbit/s to 1.5 Mbit/s. The subjective tests, including choice of method, selection of test material, and statistical analysis of results are described. The conclusions are that the hope for consistently high quality at a relatively low bit rate of, say, 256 kbit/s has not yet been fulfilled, and that some audio material still demands at least 448 kbit/s. It has also been observed that later developments of some codecs perform less well than earlier versions.
Convention Paper 7052 (Purchase now)

P11-2 The Design and Analysis of First Order Ambisonic Decoders for the ITU Layout—David Moore, Jonathan Wakefield, University of Huddersfield - Huddersfield, West Yorkshire, UK
Ambisonic decoders for irregular layouts can be designed using heuristic search algorithms. These methods provide an alternative to solving complex mathematical equations. New fitness function objectives for search algorithms are presented that ensure derived decoders meet the requirements of the Ambisonic system more closely than previous work. The resulting new decoder coefficients are compared to other published coefficients, and a detailed performance analysis of first order decoders for the ITU layout is given. This analysis highlights common poor performance characteristics that these decoders hold. Proposed future work will attempt to address these issues by looking at techniques for producing decoders with a more even error distribution around the listener and investigating methods for removing the bias toward meeting certain objectives.
Convention Paper 7053 (Purchase now)

P11-3 A New Digital Module for Variable Acoustics and Wave Field Synthesis: Design and Applications—Diemer de Vries, Delft University of Technology - Delft, The Netherlands; Jasper van Dorp Schuitman, Delft University of Technology - Delft, The Netherlands and Acoustic Control Systems, Garderen, The Netherlands; At van den Heuvel, Acoustic Control Systems - Garderen, The Netherlands
A new digital module has been developed that creates variable acoustics for multipurpose halls according to the Acoustic Control Systems (ACS) concept. Additionally, it is capable of generating wave fields according to the Wave Field Synthesis (WFS) concept. The design concepts and criteria, the technical specifications, and some first applications of the module will be explained and discussed.
Convention Paper 7054 (Purchase now)

P11-4 Artificial Reverberator with Location Control in Multichannel Recording—Hwan Shim, Jeong-Hun Seo, Koeng-Mo Sung, Seoul National University - Seoul, Korea
In this paper a novel artificial reverberator is proposed. Compared with conventional algorithms focused to append appropriate timber and reverberance, the proposed algorithm is designed to produce realistic reverberation by controlling each location of sound sources. The new algorithm proposed in this paper controls perceived direction by panning the direct sound and controls perceived distance by adjusting the energy decay curve of reverberation, which is obtained by a location-clustering method and gain of the direct sound. In addition, the algorithm enhances Listener Envelopment (LEV) to make late reverberation incoherent among channels.
Convention Paper 7055 (Purchase now)

P11-5 Spatial Audio Rendering Using Sparse and Distributed Arrays—Aki Härmä, Steven van de Par, Werner de Bruijn, Philips Research Europe - Eindhoven, The Netherlands
A widely distributed but multichannel audio reproduction system can be used to create dynamic spatial effects for various entertainment and communication applications. In this paper we focus on the follow-me audio effect where the sound source appears moving with the observer who is walking through a hallway or going from one room to another in the home environment. We give an overview of the array theory for the sparse distributed loudspeaker systems, study the binaural properties of the sound field rendered with a sparse line array, and compare two different dynamic rendering techniques in a new type of a listening test.
Convention Paper 7056 (Purchase now)

P11-6 Magic Arrays—Multichannel Microphone Array Design Applied to Multiformat Compatibility—Michael Williams, Sounds of Scotland - Paris, France
This paper describes the principles and design procedure of multiformat-compatible microphone arrays for a range of different segment coverage angles and for omnidirectional, hypocardioid, cardioid, and supercardioid microphones. At present the only practical solution available for the main microphone array for a multiple format recording is to use different microphone arrays for each of the required formats. This paper shows how this jungle of main microphone arrays can be replaced by a single 5-channel microphone array that will supply signals that are directly compatible with five standard formats: mono, 2- and 3-channel “stereo,” 4-channel “quadraphony,” and “multichannel” with the full five channels. The specific reproduction format can be chosen either during the production process as a function of the desired support media, or by the consumer from a multichannel media product according to their own particular listening configuration.
Convention Paper 7057 (Purchase now)