. Next, the sound source 00 proceeds to Step SB00. The sound source 00 judges whether the flag STF0 is set to "0" or, in other words, the impact tone waveform data reading stopped state. When the impact tone waveform data reading stopped state is set, the judgment result is "YES". The sound source 00 proceeds to Step SB00. At Step SB00, the sound source 00 decrements the impact delay time T0 read from the delay time table TBL at Step SB0, described earlier (see FIG. 0). Next, at Step SB00, the sound source 00 judges whether the decremented 