In perception of regular sequence of stimulus sounds that is neither too rapid nor too slow, we tend to perceive it as rhythmic. In the present study, we investigated the degree of temporal distortion intervened in the sequence which was needed in order for listeners to be able to report an irregularity, and we also investigated the timing patterns of the repetition of monosyllables as a response to the regular sound sequence. The degree of distortion which afforded 50% judgments of detection was found to be about 6% in the region of rates slower than 3 times per second, and about 7.6∼8.9% depending upon the type of distortion in the region of rates more rapid than 4 times per second. Another experiment showed that a negative correlation between the time intervals of neighboring vicinity which suggested an adjusting mechanism was found only in the region of rates slower than 3 times per second. From the results, the author tentatively concludes that the ongoing processing mechanism works in the region of rates slower than 3 times per second and the wholistic processing mechanism works in the region of rates more rapid than 3 times per second.