The effects of syllable structure on diadochokinetic and reading rates.

Paragraphs with controlled phonetic structures were matched to similarly structured diadochokinetic (Maximum Repetition Rate) tasks in an effort to devise a more valid measurement for (1) assessing possible relationships between diadochokinesis and speech rate, and (2) evaluating the effects on articulation rates of such structural variables as number of consonants in a syllable, and alternating versus simple syllable repetitions. Highly stable results were obtained, suggesting the possibility of a sharp neurophysiological or biomechanical barrier which varies markedly among presumably normal speakers. Maximum repetition rates were poor predictors of normal reading rate performance. On the other hand, normal reading rates were found to be approximately the same as the maximum repetition rates--about 13.5 phones per second. The inference is that normal speech is not, as commonly supposed, obviously slower than maximum rates of syllable articulation, for equivalent syllables. The major source of variation in syllable rate measures was simply the number of phones in a syllable. The effects of articulatory place and manner appeared relatively trivial by comparison.