Audio signal processor, method, and program for suppressing noise components from input audio signals

摘要

The invention provides an audio signal processing device capable of improving sound quality by causing a voice switch to operate appropriately. Delay-subtraction processing is performed on an input signal to form a first and second directional signal with nulls in a first and second specific direction, respectively, and a coherence is obtained using the two directional signals. The coherence is then compared to a determination threshold value to determine whether the input audio signal is a target-sound segment arriving from a target-direction, or a non-target-sound segment other than the target-sound segment. A gain is set according to the determination result, and any non-target-sound is attenuated by multiplying the input signal by the gain. The determination threshold value is controlled based on an average value of coherence in interfering-sound segments.

主权项

1. An audio signal processing device that suppresses noise components from input audio signals, the audio signal processing device comprising:
a first directionality forming section that by performing delay-subtraction processing on an input audio signal forms a first directional signal imparted with a directionality characteristic having a null in a first specific direction; a second directionality forming section that by performing delay-subtraction processing on the input audio signal forms a second directional signal imparted with a directionality characteristic having a null in a second specific direction different from the first specific direction; a coherence computation section that obtains a coherence using the first and second directional signals; a target-sound segment detection section that by comparing the coherence with a first determination threshold value determines whether the input audio signal is a segment of a target-sound arriving from a target direction, or a non-target-sound segment other than the target-sound segment; a target-sound segment determination threshold value controller that based on the coherence detects an interfering-sound segment from among non-target-sound segments including both the interfering-sound segment and a background noise segment, that obtains an interfering-sound average coherence value representing an average coherence value in the interfering-sound segment, and that controls the first determination threshold value based on the interfering-sound average coherence value; a gain controller that sets a voice switch gain according to a determination result of the target-sound segment detection section; and a voice switch gain multiplication section that multiplies the input audio signal by the voice switch gain obtained by the gain controller.