PURPOSE: To provide the acoustic effect device which easily adds an excellent acoustic effect to the musical performance of musical sounds by receiving a MIDI signal transmitted from an electronic musical instrument of MIDI standards and using the timing clock of this MIDI signal to automatically perform the reverberation processing of musical sounds corresrespond-ingly to the performance tempo of the electronic musical instrument.

CONSTITUTION: An acoustic effect device 1 which adds an reverberation signal to an analog or digital musical sound signal by reverberation processing means 19 and 21 to add an acoustic effect to the performance of musical sounds is provided with a reverberation time setting means 11 which sets the reverberation time and MIDI signal reception means 11 and 18 which receive the MIDI signal for control of the electronic musical instrument, and the reverberation time setting means 11 calculates the reverberation time in accordance with time intervals of the timing clock of the MIDI signal received by MIDI signal reception means 11 and 18, thereby setting the reverberation time.