PURPOSE: To obtain an acoustic effect having a spread by providing a storage means, a read means, a sympathetic sound producing means, an operator, and an output means.

CONSTITUTION: For example, sounds which are not accompanied with the operation of a damper pedal are picked up from the piano, and their acoustic waveforms is stored in a memory 10. A sympathetic sound producing means 32 is provided which produces sympathetic sound information based on the acoustic waveform stored in this memory 10, and the acoustic waveform stored in the memory 10 is read out by a read means 20 to generate a musical sound signal at the time of not operating an operator 26 like the pedal, and sympathetic sound information is outputted as the musical sound signal at the time of operating the operator 26, thereby faithfully simulating the damper pedal effect. Thus, the acoustic effect having a spread is obtained.