Exploring the relationship of inspiration duration to utterance duration.

Previous work has indicated that there may be a positive relationship between the duration and extent of inspiration and the length of an upcoming utterance. However, none of that work has uniquely implied a role of planning. We attempted to avoid some of the alternative explanations by forcing subjects to utter single sentences ranging in length from 5 to 82 syllables (mean of 27), after inspiring fully and then expiring down to a set level before uttering the sentence. For all 3 subjects, there was a significant positive relationship between utterance length and inspiration duration, regardless of whether inspiration was measured physiologically or acoustically. The 2 subjects with the higher correlations in the articulatory measures also expended air more quickly during the shorter sentences than longer ones, while the other subject had no correlation with exhalation rate. Complexity of the sentence, calculated as the number of clauses in the sentence, did not affect inspiration duration. The individual differences need further investigation, but there is a positive correlation between the duration of the sentence to be said and the inspiration before it when the speaker is required to read sentences while using only one breath.