Multichannel Room Correction with Focus Control

Lars-Johan Brännmark, and Anders Ahlén

Journal of the Audio Engineering Society, , vol. 63, no. 1/2, pp. 21-30, January/February 2015.
© 2015 AES

Abstract:

Digital equalization of audio systems is mostly performed on a channel-by-channel basis, i.e., loudspeakers are equalized separately and independently of each other. In reverberant rooms the spatial variability of the loudspeaker–room transfer function puts a limit on what can be achieved with such single-channel approaches, and considerably more far-reaching results can be obtained with multichannel methods.

In this paper we present a multichannel equalizer design method where the loudspeaker to be equalized is assisted by several support loudspeakers that act in combination to improve the response of the main loudspeaker while suppressing the reverberation of the listening room. However, since a full dereverberation may not always be desirable, we shall here study the proposed method from the perspective of how to control the amount of room correction for a given number of contributing support loudspeakers.

The amount of correction is controlled by a scalar parameter that we interpret as a “focus control,” enabling the user to slide seamlessly between a single-channel equalizer and a full multichannel inversion of the room.

Related publications:

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