120th AES Convention - Paris, France - Dates: Saturday May 20 - Tuesday May 23, 2006 - Porte de Versailles

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AES Paris 2006

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P14 - Posters: Multichannel Sound

Sunday, May 21, 16:00 — 17:30

P14-1 Effectiveness of Height Information for Reproducing the Presence and Reality in the Multichannel Audio SystemKimio Hamasaki, Toshiyuki Nishiguchi, NHK Science & Technical Research Laboratories - Tokyo, Japan; Koichiro Hiyama, NHK Kumamoto Station - Kumamoto, Japan; Reiko Okumura, NHK Science & Technical Research Laboratories - Tokyo, Japan
A 22.2 multichannel sound system was developed that adapts to an ultrahigh-definition video system with 4000 scanning lines. The sound system consists of loudspeakers with three layers: an upper layer with nine channels, a middle layer with ten channels, and a lower layer with three channels and two channels for low frequency effects. This system has new features of three-dimensional sound reproduction. Subjective evaluation by the semantic differential (SD) method are presented to assess the importance of height information for a sound system using several stimuli in a 22.2 multichannel audio system with Super Hi-Vision and a high-definition television. Furthermore, the actual effectiveness of height information and some practical suggestions for aesthetic mixing of three-dimensional audio is also presented.

[Poster Presentation Associated with Paper Presentation P7-1]
Convention Paper 6679 (Purchase now)

P14-2 Miniature Microphone Arrays for Multichannel RecordingJuha Backman, Nokia Corporation - Espoo, Finland
This paper describes a method of using a dense array of miniature microphones (e.g., MEMS or miniature electret) to yield precise one-point multichannel gradient microphones. The signals obtained from individual microphones in the array are used to obtain an estimate for the zero, first-, and second-order components of the gradient of the sound field at the center of the array. (Higher orders of the gradient tend to be too noisy for actual sound recording purposes.) These can be used to form stereo or multichannel signals with adjustable polar patterns for recording purposes.

[Poster Presentation Associated with Paper Presentation P7-3]
Convention Paper 6681 (Purchase now)

P14-3 Benefits of Distance Correction for Multichannel MicrophonesThomas Görne, Detmold University of Music - Detmold, Germany
Subjective assessment of stereophonic or multichannel microphone techniques often suffers from differences in the diffuse field sensitivities of various arrays. Diffuse field behavior of single rotation-symmetrical microphones at lateral direct sound incidence can be derived from the polar equations of ideal first-order gradient transducers. This simple model is used to estimate distance correction factors for symmetrical two-dimensional arrays as well as for MS pairs. The benefits of corrected stereo setups are also investigated.

[Poster Presentation Associated with Paper Presentation P7-4]
Convention Paper 6682 (Purchase now)

P14-4 Virtual Source Location Information-Based Matrix Decoding SystemHan-gil Moon, Manish Arora, Samsung Electronics Co. Ltd. - Suwon, Gyeonggi-Do, Korea
In this paper a new matrix decoding system using vector-based Virtual Source Location Information (VSLI) is proposed as one alternative to the conventional Dolby Pro logic II/IIx system for reconstructing multichannel output signal from matrix encoded 2-channel signals, Lt/Rt. This new matrix decoding system is composed of a passive decoding part and an active part. The passive part makes crude multichannel signals using a linear combination of the two encoded signals(Lt/Rt), and the active part enhances each channel regarding the virtual source, which is emergent in each inter channel. The virtual sources between channels are estimated by the inverse constant power panning law.

[Poster Presentation Associated with Paper Presentation P7-5]
Convention Paper 6683 (Purchase now)

P14-5 Quality Degradation Effects Caused by Limiting the Bandwidth of Standard Surround Sound Channels and Hierarchically Encoded MSBTF Channels: A Comparative StudyYu Jiao, Slawomir Zielinski, Francis Rumsey, University of Surrey - Guildford, Surrey, UK
Limiting the bandwidth of multichannel audio can be used as an effective method of trading-off audio quality with broadcasting costs. In this paper subjective effects of two controlled high-frequency limitation methods on multichannel audio quality were studied with formal listening tests. The first method was based on limiting the bandwidth of standard surround sound channels (Rec. ITU-R BS. 775-1); the second involved limiting the bandwidth of the hierarchically encoded MSBTF channels. The results are compared and discussed. In this experiment, the low frequency effect (LFE) channel was omitted.

[Poster Presentation Associated with Paper Presentation P7-7]
Convention Paper 6685 (Purchase now)

P14-6 Initial Developments of an Objective Method for the Prediction of Basic Audio Quality for Surround Audio RecordingsSunish George, Slawomir Zielinski, Francis Rumsey, University of Surrey - Guildford, Surrey, UK
This paper describes the development of the objective method for the prediction of the Basic Audio Quality (BAQ) of band-limited or down-mixed surround audio recordings. A number of physical parameters, including interaural cross-correlation coefficients and spectral descriptors, were extracted from the recordings and used in a linear regression model to predict BAQ scores obtained from listening tests. The results showed a high correlation between the predicted scores and those obtained from the listening test, with the average error of prediction being smaller than 10 percent. Although the method was originally developed for 5-channel surround recordings, after some modifications it can be upgraded to any number of audio channels.

[Poster Presentation Associated with Paper Presentation P7-8]
Convention Paper 6686 (Purchase now)

P14-7 Tactile Strategies and Resources for Teaching Multichannel Sound ConceptsLeslie Gaston, University of Colorado at Denver - Denver, CO, USA
Several university audio programs now incorporate multichannel, or surround sound, into their curricula. In order to supplement these courses and lectures many opportunities exist to incorporate hands-on demonstrations of concepts used for microphone techniques, mixing, monitoring, and delivery. This paper will give suggestions for different tactile strategies that can be used to illustrate concepts in multichannel audio, as well as other resources that may be utilized when doing preparation and research for teaching classes. Suggestions for homework and research topics for students will also be provided, along with recommended equipment needs.

[Poster Presentation Associated with Paper Presentation P7-11]
Convention Paper 6689 (Purchase now)

P14-8 Spatial Aliasing Artifacts Produced by Linear and Circular Loudspeaker Arrays Used for Wave Field SynthesisSascha Spors, Deutsche Telekom Laboratories - Berlin, Germany; Rudolf Rabenstein, University of Erlangen-Nuremberg - Erlangen, Germany
Wave field synthesis allows the exact reproduction of sound fields if the requirements of its physical foundation are met. However, the practical realization imposes certain technical constraints. One of these is the application of loudspeaker arrays as an approximation to a spatially continuous source distribution. The effect of a finite spacing of the loudspeakers can be described as spatial sampling artifacts. This contribution derives a description of the spatial sampling process for planar linear and circular arrays, analyzes the sampling artifacts, and discusses the conditions for preventing spatial aliasing. It furthermore introduces the reproduced aliasing-to-signal ratio as a measure for the energy of aliasing contributions.

[Poster Presentation Associated with Paper Presentation P11-2]
Convention Paper 6711 (Purchase now)

P14-9 Characterization of the Reverberant Sound Field Emitted by a Wave Field Synthesis Driven Loudspeaker ArrayTerence Caulkins, Olivier Warusfel, IRCAM - Paris, France
Realistic sound reproduction using wave field synthesis (WFS) in concert halls involves ensuring that both the direct and reverberated sound fields are accurate at all listening positions. Though methods for controlling the direct sound field have been described in the past, the control of the reverberated sound field associated to WFS sources remains a topic of interest. This paper describes the characteristics of the reverberated sound field associated to a WFS array as it synthesizes a virtual point source. Variations in the directivity and positioning of the virtual source are shown to have an effect on the associated room effect. A solution for controlling the reverberated sound field in a concert hall equipped with a WFS system is proposed based on this characterization.

[Poster Presentation Associated with Paper Presentation P11-3]
Convention Paper 6712 (Purchase now)

P14-10 Virtual Concert: Spatial Sound in DVD TechnologyDavid Gordon, Glasgow Caledonian University - Glasgow, UK
This paper documents the use of spatial sound in DVD technology. It sets out to evaluate the communicative abilities of spatial sound and the implications of combining spatial sound along with selective multiple camera angles. We also Increase the rationale by investigating the use of a nonlinear structure in the presentation of audio-visual DVD products. We assert that no product currently integrates these deconstructed components into a singular framework, and therefore reports on the development of a concept titled Virtual Concert. The paper also discusses the underlying concept of Virtual Concert in relation to the combination of surround sound music mixes with the corresponding camera angle, presented in a nonlinear structure. The emphasis is on practical subjective evaluation through a screening of Virtual Concert and subsequent distribution of comprehensive questionnaires.
Convention Paper 6731 (Purchase now)

P14-11 The Adaptation of Concert Hall Measures of Spatial Impression to Reproduced SoundJonathan Hirst, William J. Davies, University of Salford - Salford, UK; Peter Philipson, Liverpool Institute for Performing Arts - Liverpool, UK
A method of objectively measuring the spatial capabilities of multichannel sound systems has been investigated. The method involved the comparison of interaural cross correlation (IACC) measurements taken in a concert hall to IACC measurements taken in reproduced versions of the same concert hall. The type of reproduction system was varied, and an indication of the spatial capabilities of each system was gained from the comparison of original and reproduced IACC measurements. The comparisons revealed that all the reproduction systems were unable to match the lowest IACC readings taken in the concert hall, and that the measurement method was capable of discriminating between the spatial performance of the reproduction systems and also to rank the system's performances in an expected order.
Convention Paper 6732 (Purchase now)

P14-12 Analysis of Spatial Resolution of Multiactuator PanelsBasilio Pueo, Sergio Bleda, University of Alicante - Alicante, Spain; José Escolano, José Javier Lopez, Technical University of Valencia - Valencia, Spain
A study of the aliasing frequency of Multiactuator Panels (MAPs) with application to Wave Field Synthesis (WFS) is presented. It is based on the periodicity of the spatial frequency in a wave number domain. The success of these loudspeakers for WFS lies in the absence of exciter cross interference, acting as single sources. However, the distance between exciters may not be indicative of the spatial resolution capability of the array. A set of four MAPs comprising 15 exciters were measured by using this multidimensional analysis. An additional dynamic loudspeaker array having the same loudspeaker spacing was also measured. Results confirm the diffuse radiation of MAPs and the superior performance when generating axial plane waves with respect to dynamic loudspeakers. Finally, there are little differences in the aliasing frequency with that expected from the distance between exciters.
Convention Paper 6733 (Purchase now)

P14-13 New CLD Quantization Method for Spatial Audio CodingYang-Won Jung, Hyen-O Oh, Hyo Jin Kim, Seung Jong Choi, LG Electronics - Seoul, Korea
In spatial audio coding, spatial parameters, such as CLDs, CPCs, and ICCs, are utilized for downmix and upmix of the multichannel audio signals. In the current version of MPEG Surround, a universal quantization table for CLD is applied independent to channel combinations. As intervals between adjacent channels differ in the conventional 5.1-channel configuration, this universal quantization scheme causes redundancies in some combinations while insufficiencies are caused in the other combinations. In this paper we propose a new CLD quantization method based on well-known amplitude panning law and spatial resolution of human perception. By the proposed quantization method, CLD can be represented more efficiently, and therefore, bit reduction and quality enhancement can be achieved.
Convention Paper 6734 (Purchase now)

  (C) 2006, Audio Engineering Society, Inc.