Audio processing apparatus

An audio processing apparatus, comprising:

• a first microphone which converts a first sound to a first electric signal;
• a preprocessor which extracts a voice-band signal from the first electric signal, and outputs a first output signal containing the voice-band signal;
• a first controller which generates a first amplification coefficient to be multiplied with the first output signal to compress a dynamic range of an intensity of the first output signal, and generates a first modified amplification coefficient by smoothing the first amplification coefficient with a first time constant;
• a first multiplier which multiplies the first modified amplification coefficient and the first output signal;
• a second microphone which converts a second sound to a second electric signal;
• a second controller which generates a second amplification coefficient to be multiplied with a second output signal according to the second electric signal to compress a dynamic range of an intensity of the second output signal, and generates a second modified amplification coefficient by smoothing the second amplification coefficient with a second time constant;
• and
• a second multiplier which multiplies the second modified amplification coefficient and the second output signal,
• wherein the first time constant is a first rise time constant when the intensity of the first output signal increases, and is a first decay time constant when the intensity of the first output signal decreases,
• the second time constant is a second rise time constant when the intensity of the second output signal increases, and is a second decay time constant when the intensity of the second output signal decreases, and
• the first rise time constant is greater than the second rise time constant.