Patent ID: 8364478

Claim:
An audio signal processing apparatus, comprising at least: an environmental ambient noise level detection unit for detecting an environmental ambient noise level contained in an audio signal input through sound collection means for collecting a transmission sound at a time of a voice call; a signal level adjustment unit which has (a) a level adjustment function to adjust a predetermined formant component for an output signal level with respect to an input signal level, and (b) an input/output characteristic change function to change an input/output characteristic when adjusting a level in the level adjustment function by means of a control signal, and in which a received sound signal in the case of a telephone voice call is arranged to be an input signal, wherein the predetermined formant component has a frequency band which does not overlap with a peak of environmental ambient noise; and a control signal generation unit for generating the control signal for changing the input/output characteristic of the signal level adjustment unit from the environmental ambient noise level detected by the environmental ambient noise level detection unit.