Adaptive Algorithm of Iterative Inverse Filter Relaxation to Acoustic Fluctuation in Sound Reproduction System

In this paper, we newly propose an adaptive relaxation algorithm for inverse filter design of the multichannel sound reproduction system. The inverse filter of the conventional method often amplifies the background noise and line noise when the room transfer function changes. In order to resolve the problem, the adaptive relaxation algorithm based on the truncated singular value decomposition (TSVD) method is introduced, in which only one microphone to observe the noise condition is placed apart from listener’s ears. First, desired signals are reproduced at all control points for listening and control point for noise observation. Next, the number of truncated singular values of matrix composed of room transfer functions is determined based on the observed noise. The experimental result of the computer simulation using real environmental data reveals that the proposal method can prevent the noise amplification. The subjective evaluation in the real sound reproduction system also indicates the trade-off relation between the sound quality and the localization.