An acoustic signal processing apparatus which is configured to receive an input acoustic signal and form an output acoustic signal which is to be supplied to a sound system including an amplifier and a speaker, the acoustic signal processing apparatus comprising: a band separation portion (13, 14, 15) for separating the input acoustic signal into a high frequency component, a middle frequency component and a low frequency component; a first level control portion (16, 21) for controlling a level of the high frequency component in accordance with a first control signal to output the controlled high frequency component; a second level control portion (17, 24) for controlling a level of the low frequency component in accordance with a second control signal to output the controlled low frequency component; a mixing portion for mixing - a band component originating from the controlled high frequency component output from the first level control portion, - a band component originating from the middle frequency component output from the band separation portion and - a band component originating from the controlled low frequency component output from the second level control portion to output a mixed signal; a first control signal generation portion which is configured to detect a volume level of the mixed signal to generate the first control signal in accordance with the detected volume level; and a second control signal generation portion (22, 23) which is configured to detect a volume level of said band component originating from the controlled low frequency component or a volume level of a low frequency component of the mixed signal to generate the second control signal in accordance with the detected volume level. a band separation portion (13, 14, 15) for separating the input acoustic signal into a high frequency component, a middle frequency component and a low frequency component; a first level control portion (16, 21) for controlling a level of the high frequency component in accordance with a first control signal to output the controlled high frequency component; a second level control portion (17, 24) for controlling a level of the low frequency component in accordance with a second control signal to output the controlled low frequency component; a mixing portion for mixing - a band component originating from the controlled high frequency component output from the first level control portion, - a band component originating from the middle frequency component output from the band separation portion and - a band component originating from the controlled low frequency component output from the second level control portion - a band component originating from the controlled high frequency component output from the first level control portion, - a band component originating from the middle frequency component output from the band separation portion and - a band component originating from the controlled low frequency component output from the second level control portion to output a mixed signal; a first control signal generation portion which is configured to detect a volume level of the mixed signal to generate the first control signal in accordance with the detected volume level; and a second control signal generation portion (22, 23) which is configured to detect a volume level of said band component originating from the controlled low frequency component or a volume level of a low frequency component of the mixed signal to generate the second control signal in accordance with the detected volume level.