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Aalto

Perceptual Studies on Spatial Sound Reproduction Systems

Nick Zacharov

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 15th of December, 2000, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-5210-4)   [907 KB]
Dissertation is also available in print (ISBN 951-22-5209-0)

Abstract

This study considers research on spatial sound perception in the context of multichannel and other spatial sound reproduction systems. Issues associated with multichannel level alignment are discussed. Additionally aspects relating to the quality of spatial sound reproduction associated with loudspeaker directivity and 3D sound algorithms are considered. Lastly, a study of spatial sound perception is unfolded.

This thesis contributes to the understanding of level alignment techniques from both a subjective and objective standpoint in multichannel sound reproduction schemes. The aim of these subjective experiments was to obtain a database of subject responses for a level alignment task under a wide range of normal usage situations, accounting for different source locations, distances, directivities, sensitivities, bandwidths and absolute reproduction levels. The data was analysed and correlated with a set of objective metrics measured for each test condition. From this analysis it is possible to ascertain superior test signal/metric combinations for perceptually motivated level alignment. Results may be directly applied to automated level calibration systems. Tools for binaural real-time loudness measurement are introduced allowing for the assessment of directional loudness characteristics and multiple source loudness alignment within arbitrary reveberation spaces.

The second set of experiments focuses on issues influencing the quality of spatial sound reproduction under different multichannel sound reproduction scenarios. Firstly, the influence of loudspeaker directivity is subjectively assessed in a discrete five channel multichannel scenario. A set of experiments are presented that assess the influence of directivity both in the frontal and surround loudspeakers under idealised listening conditions.

A range of virtual home theater systems are reviewed and a benchmark experiment is presented that compares their performance with respect to a discrete five channel multichannel reproduction. Evaluations are performed in an idealised "standard listening room" and real room conditions. Relative performances of each system are discussed in terms of relative spatial and timbral degradation.

Lastly, initial studies are presented into the multidimensional perceptual unfolding of spatially processed speech reproduced over headphones. This study provides the basis for further studies in this area in an attempt to unravel or "unfold" the perceptual dimensions associated with spatial sound reproduction.

This thesis consists of an overview and of the following 9 publications:

  1. N. Zacharov. An overview of multichannel level alignment. In Proceedings of the Audio Engineering Society 15th Int. Conf., pages 174-186, Denmark, October, 1998. © 1998 AES. By permission.
  2. P. Suokuisma, N. Zacharov and S. Bech. Multichannel level alignment, part I: signals and methods. In Proceedings of the Audio Engineering Society 105th Int. Conv., preprint 4815, San Francisco, 26-29 September, 1998. © 1998 AES. By permission.
  3. N. Zacharov, S. Bech and P. Suokuisma. Multichannel level alignment, part II: The influence of signals and loudspeaker placement. In Proceedings of the Audio Engineering Society 105th Int. Conv., preprint 4816, San Francisco, 26-29 September, 1998. © 1998 AES. By permission.
  4. S. Bech and N. Zacharov. Multichannel level alignment, part III: The effects of loudspeaker directivity and reproduction bandwidth. In Proceedings of the Audio Engineering Society 106th Int. Conv., preprint 4909, Munich, 8-11 May, 1999. © 1999 AES. By permission.
  5. N. Zacharov and S. Bech. Multichannel level alignment, part IV: The correlation between physical measures and subjective level calibration. In Proceedings of the Audio Engineering Society 109th Int. Conv., preprint 5241, Los Angeles, 22-25 September, 2000. © 2000 AES. By permission.
  6. O. Tuomi and N. Zacharov. A real-time binaural loudness meter. Presented at the 139th meeting of the Acoustical Society of America, Atlanta, USA, June, 2000. © 2000 by authors.
  7. N. Zacharov. Subjective appraisal of loudspeaker directivity for multichannel reproduction. Journal of the Audio Engineering Society, 46(4):288-303, April 1998. © 1998 AES. By permission.
  8. N. Zacharov and J. Huopaniemi. Results of a round robin subjective evaluation of virtual home theatre sound systems. In Proceedings of the Audio Engineering Society 107th Int. Conv., preprint 5067, New York, 24-27 Sept. 1999. © 1999 AES. By permission.
  9. W.L. Martens and N. Zacharov. Multidimensional Perceptual Unfolding of Spatially Processed Speech I: Deriving Stimulus Space using INDSCAL. In Proceedings of the Audio Engineering Society 109th Int. Conv., preprint 5224, Los Angeles, 22-25 September, 2000. © 2000 AES. By permission.

Keywords: multichannel, loudness, listening tests, subjective evaluation, spatial sound, 3D audio, perception, multidimensional unfolding, INDSCAL

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© 2000 Helsinki University of Technology

Last update 2011-05-26