Constancy of relative timing for stutterers and nonstutterers.

Fifteen stutterers and 15 nonstutterers read a 120-word passage five times in succession. From the stutterers' readings, sentences were selected for analysis that were produced fluently in the first and the fifth reading. The sentences surrounding the target utterance in the first reading, however, contained instances of stuttering although the surrounding sentences in the fifth reading were fluent. The same utterances were selected from the first and fifth readings produced by the nonstutterers, but the surrounding sentences were fluent for both samples. Four separate relative timing ratios were defined by measuring an acoustic period and an acoustic latency and dividing the period by the latency. Analysis of the ratios revealed no significant differences between the groups in spite of the rate changes that occurred between the readings. The data indicate that not all aspects of a stutterer's speech are affected by the stuttering, and that relative timing may be a critical parameter for the production of fluent utterances.