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Session L Monday, May 14 13:30 - 18:00 hr Room C/D

Multichannel Sound

Chair: Wieslaw Woszcyk, McGill University, Montreal, Canada

13:30 hr L-1
Multichannel and "SOR" Principles for Conferencing and Teleconferencing Systems
Peter Fels
T-Nova Deutsche Innovations, Berlin, Germany

A multichannel sound for a teleconferencing system with better sound quality and wide-band multichannel sound production, transmission and reproduction is described. This method has the advantages of the coincidence of visual and auditory perspective, of the minimum of feedback a.s.o. The first part treads a modern solution to optimizing the technology of the multichannel production and the minimizing of echo and noise. The second part treads the complete solution with large picture. The third part shows the applications of the principles of the Delta-Stereophony-Systems (SOR) for multichannel conferencing systems.
Paper 5366

14:00 hr L-2
Stereo+C: An All-Purpose Arrangement of Microphones using Three Frontal Channels
Andreas Gernemann
University of Cologne, Cologne, Germany

Until now, considerations for the arrangement of microphones using three frontal channels based on ITU-R BS 755-1 recommendation assume that three frontal speakers are set up in equal height and equal distance in front of a listener. Unfortunately in most home applications the center speaker is not set up as required by the ITU standard. In addition most of these microphone techniques are not compatible with two channel stereo. Stereo+C is an arrangement that allows to use normal stereo microphone techniques with an additional specially arranged center microphone. The entire arrangement is completely stereo compatible and uncritical in case of a non-ideal loudspeaker set up at the consumer's home.
Paper 5367

14:30 hr L-3
Optimization and Subjective Assessment of Surround Sound Microphone Arrays
Paul Segar & Francis Rumsey
University of Surrey, Guildford, UK

A number of surround sound arrays have been constructed with closely spaced microphones of cardioid and omni-directional patterns. The spacing and angles between microphones were calculated to test two different psychoacousticsí models that aim to provide 360ƒ imaging in a horizontal plane. A series of controlled subjective listening tests have been undertaken, and results are presented comparing image localization accuracy and localization confidence between the arrays. Results on the effect of cross-talk between opposite microphones in the arrays are also presented.
Paper 5368

15:00 hr L-4
Metering for Multichannel Audio
John Emmett (1) & Chas Kennedy (2)
Broadcast Project Research, Teddington, UK
Canford Audio, Washington, UK

This paper raises a debate about the future options that are open for multichannel audio metering in Television and Radio Production. These options are seen both in the light of experience with Movie production, and also as a part of the wider issue when metering is applied to legacy applications. In particular, the study questions the continued relevance of signal level metering within all-digital audio chains. It also concentrates on the importance of dialogue loudness and intelligibility, when that dialogue may form an integral part of several different audio delivery packages. Finally, the visual perceptual aspect of various types of meter display is seen to be an important but neglected aspect of the overall measurement process.
Paper 5369

15:30 hr L-5
Recent Developments on WFS for High Quality Spatial Sound Reproduction
Rinus Boone, Werner de Bruijn & Wilfred van Rooijen
Technical University Delft, Delft, The Netherlands

Wave Field Synthesis (WFS) is a method to reproduce spatial sound with a correct localization over a large listening area. It enables a high quality sound reproduction of sound objects according to, for instance, the MPEG-4 standard, but also compatible reproduction of 2/0 and 3/2 sound material. Recent developments will be presented concerning true perspective acoustic reproduction, also in combination with video projection, making use of different types of loudspeaker arrays, including multi-exciter DML-panels.
Paper 5370

16:00 hr L-6
Computation of Generalized Mutual Information from Multichannel Audio Data
Josh Reiss, Mark Sandler & Nikolaos Mitianoudis
King's College, London, UK

The authors present a new method to extract the mutual information for data from any number of channels from either a discrete or continuous system. This generalized mutual information allows for the estimation of the average number of redundant bits in a vector measurement. Thus it provides insight into the information shared between all channels of the data. It may be used as a measure for the success of blind signal separation with multichannel audio. Several multichannel audio signals are separated using various ICA methods and the mutual information of each signal is computed and interpreted. It is also implemented as a contrast function in ICA for a new method of blind signal separation.
Paper 5371

16:30 hr L-7
Optimal Source Distribution System for Virtual Acoustic Imaging
Takashi Takeuchi & Philip Nelson
University of Southampton, Southampton, UK

When binaural sound signals are presented with loudspeakers, the system inversion involved gives rise to a number of problems such as, for example, loss of dynamic range and a lack of robustness to small errors of control performance. These problems for such systems are investigated and this has resulted in the proposal of a new system, the Optimal Source Distribution ("OSD") system, which overcomes these problems by means of variable transducer span. A practical solution to realize a variable transducer span by discretization is also described. Several examples of the "OSD" system are demonstrated which in practice produce a very robust system over the whole audible frequency range. The relationship to the "Stereo Dipole" system is also described.
Paper 5372

17:00 hr L-8
Surround Sound Impact over Large Areas
Christian Landone (1) & Mark Sandler (2)
 Feline Records, London, UK
 King's College, London, UK

Multichannel sound systems have been extensively used in sound reinforcement applications and in other large installations but the overall impact on audiences still remains an unknown at the design stage. This paper highlights some of the challenges involved in predicting the spatial reproduction performance of surround sound systems serving large and acoustically live listening areas and highlights the shortcomings of current objective assessment methods.
Paper 5373

17:30 hr L-9
Problems Related to Surround Sound Production
Artur Kornacki, Bozena Kostek, Piotr Odya & Andrzej Czyzewski
Technical University of Gdansk, Gdansk, Poland

The problem of production of recordings designated for surround sound systems becomes a vital problem in sound technology. Existing standards of surround systems allow for reproduction of spatial sound. However, there are no consistent recommendations as to which microphone and mixing technique could be used in specific situations. For the purpose of research presented in this paper several microphone techniques were employed for recordings of a quartet playing classical music. The mixing results in two-channel excerpts and several multichannel ones designated for 5.1 reproduction system. Then, in order to find the most preferable recording technique these excerpts were used in subjective tests.
Paper 5374


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