An audio signal processing apparatus comprising: an acquiring unit which is adapted to acquire a multi-channel audio signal and to output an audio signal, in which at least two channels of the multi-channel audio signal are added to each other; a first filtering unit (120, 130) which is adapted to output the audio signal output by the acquiring unit to the first filtering unit (120, 130) while attenuating frequency components of the audio signal except for frequency components of a first preset frequency band; a detecting unit which is adapted to detect a sound volume level of the audio signal (St) output from the first filtering unit; an amplitude limiting unit which is adapted to calculate, as an amplitude limiting level, a constant percentage of the sound volume level detected by the detecting unit, and which is adapted to limit an amplitude of a waveform of the audio signal (Sa) output from the first filtering unit at a level equal to the amplitude limiting level, thereby outputting an audio signal (Sb) to which harmonics are added; a second filtering unit (150, 160, 165) which is adapted to output the audio signal (Sc) output from the amplitude limiting unit while attenuating frequency components of the audio signal except for frequency components of a second preset frequency band including at least a part of the frequency band of the audio signal output from the first filtering unit, and a part of the frequency band of the harmonics; a compressing unit which is adapted to output the audio signal (Sd) output from the second filtering unit while compressing a dynamic range of the audio signal; and an adding unit which is adapted to add the audio signal (Sd) output from the compressing unit to each channel of the multi-channel audio signal, and to output a result of the addition. an acquiring unit which is adapted to acquire a multi-channel audio signal and to output an audio signal, in which at least two channels of the multi-channel audio signal are added to each other; a first filtering unit (120, 130) which is adapted to output the audio signal output by the acquiring unit to the first filtering unit (120, 130) while attenuating frequency components of the audio signal except for frequency components of a first preset frequency band; a detecting unit which is adapted to detect a sound volume level of the audio signal (St) output from the first filtering unit; an amplitude limiting unit which is adapted to calculate, as an amplitude limiting level, a constant percentage of the sound volume level detected by the detecting unit, and which is adapted to limit an amplitude of a waveform of the audio signal (Sa) output from the first filtering unit at a level equal to the amplitude limiting level, thereby outputting an audio signal (Sb) to which harmonics are added; a second filtering unit (150, 160, 165) which is adapted to output the audio signal (Sc) output from the amplitude limiting unit while attenuating frequency components of the audio signal except for frequency components of a second preset frequency band including at least a part of the frequency band of the audio signal output from the first filtering unit, and a part of the frequency band of the harmonics; a compressing unit which is adapted to output the audio signal (Sd) output from the second filtering unit while compressing a dynamic range of the audio signal; and an adding unit which is adapted to add the audio signal (Sd) output from the compressing unit to each channel of the multi-channel audio signal, and to output a result of the addition.