Uppsala universitet

Improved Loudspeaker-Room Equalization using Multiple Loudspeakers and MIMO Feedforward Control.

Lars-Johan Brännmark, Adrian Bahne , and Anders Ahlén

IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2012, Kyoto, Japan, 25-30 March 2012, pp. 237-240.
DOI: 10.1109/ICASSP.2012.6287861
© 2012 IEEE


Abstract:
In this paper, a new multichannel approach to robust loudspeaker-room equalization is presented. Traditionally, the equalization (or room correction) problem has been treated mostly by single-channel methods, with loudspeaker signals being prefiltered individually by separate scalar filters.

Single-channel methods can generally improve the average spectral flatness of the acoustic transfer functions in a listening region, but the variability of the transfer functions within the region cannot be affected. Most modern audio reproduction systems, however, contain two or more loudspeakers, and in this paper we aim at improving the equalization performance by using all available loudspeakers jointly.

To this end we propose a general MIMO formulation of the problem, which is a multichannel generalization of an earlier single-channel approach by the authors. The new approach is found to reduce the average reproduction error and the spatial variability of the acoustic transfer functions.

Moreover, pre-ringing artifacts are avoided, and the reproduction error below 1000 Hz is significantly reduced with an amount that scales with the number of loudspeakers used.

Related publications:
PhD Thesis by Adrian Bahne

Later, more extensive, Paper in IEEE TASLP 2013 on compensation of loudspeaker-room responses in a robust MIMO control framework.

Paper in IEEE SP 2013 on symmetric loudspeaker-room equalization utilizing a pairwise channel similarity criterion.


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