elay time table TBL depending on the velocity has elapsed, the sound source 00 generates the shelf board impulsive sound from the impact waveform data. The sound source 00 adds the generated hammer string-striking sound and shelf board impulsive sound and outputs the added hammer string-striking sound and shelf board impulsive sound. As a result, the relationship between the shelf board impulsive sound and the hammer string-striking sound can be simulated, and the tone variations of the acoustic piano can be actualized