On-line adaptive algorithm to acoustic fluctuation for inverse filter relaxation in sound reproduction system

This paper proposes a on-line adaptive relaxation algorithm for inverse filter. The inverse filter of the conventional method often amplifies the background noise and line noise when the room transfer function changes. To resolve this problem, an iterative relaxation algorithm for inverse filter by truncated singular value decomposition (Adaptive TSVD) have been proposed. However, it is difficult to apply this relaxation method in a duration where the original signal contains the sound. Therefore, we extend Adaptive TSVD into an on-line type algorithm based on the observed signal at the only one control point, normalizing the observed signal with the original sound. The result of the simulation reveals that the proposed method can always carry out the relaxation process against to acoustic fluctuation in any time durations. Also, subjective evaluation in the real acoustic environment indicates that the sound quality improves without degrading the localization.