Spatial Sound Reproduction Using Higher Order Loudspeakers

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• Thushara Abhayapala, The Australian National University
• Friday 03 June 2011, 11:30-13:00
• Room 503.

If you have a question about this talk, please contact p.naylor.

Sound reproduction systems aim to reproduce an arbitrary desired sound field over a volume of space. The desired sound field properties are either synthetically generated or recorded in the field using a microphone array. There are two main approaches to Spatial Sound reproduction: (i) based on cylindrical 2D or spherical 3D harmonic expansions of a sound field, and (ii) is based on the Kirchhoff-Helmholtz (K-H) integral formula (or Wave Field Synthesis). The accuracy of spatial sound systems is governed by the wavelength and the size of the region over which accurate reproduction is required. For wave number k and reproduction radius R the number of required loudspeakers is given approximately by L = 2kR +1 in the 2D case and, by (KR+1)^2 in the 3D case. Hence, large numbers of loudspeakers are required for the reproduction of high frequencies over significant areas. It is typically infeasible to employ the required number of loudspeakers in a sound reproduction setup in the home. A second limitation of sound reproduction systems is that the loudspeaker sound fields reflect from room surfaces, creating a reverberant field inside the reproduction region, which corrupts the reproduced field. This talk considers the reproduction of sound fields using arrays of higher order loudspeakers and show that we can control a given spatial sound field with a significant less loudspeakers at the expense of increased complexity in each unit. Further, we show that exterior and interior cancellation can be achieved using higher order loudspeakers.

Biography: Thushara Abhayapala received the BE degree in interdisciplinary systems engineering in 1994, and the Ph.D. degree in telecommunications engineering in 1999 from the Australian National University (ANU). Currently, he is the Director of the Research School of Engineering at ANU . His research interests are in physically inspired signal processing problems in the areas of Acoustic and Audio; Wireless and Mobile Communications; and Bio-medical applications. These include broadband/ nearfield beamforming, array signal processing, wireless channel modelling, sound propagation modelling, and spatial soundfield recording and reconstruction. He is an Associate Editor for EURASIP Journal on Wireless Communications and Networking and he is a member of the IEEE Audio and Acoustics Signal Processing Technical Committee.

This talk is part of the COMMSP Seminar series.

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