Periodic variation in inspiratory volume characterizes speech as well as quiet breathing

Variability in inspired lung volume prior to speech is only partially accou nted for by speech-related concerns such as the length and loudness of the planned utterance. Control mechanisms known to influence volume variability in nonspeech breathing could potentially account for some of this variabil ity, but only if they operate during speech as well. This investigation was designed to test for the presence of several such mechanisms: during readi ng aloud. Lung volumes were recorded from 5 normal females as they read sil ently, then aloud. Inspired volumes were correlated with the volumes of the previous and following expirations and with inspiratory duration. Coeffici ents of variation were calculated for inspiratory volume, duration, and mea n flow. Time-series analyses were used to compare periodicity in inspired v olume for quiet and speech breathing. Control mechanisms operating during b oth quiet breathing and reading aloud included slow oscillations in inspire d volume and minimized variability in mean flow. Inspired volume prior to s peech was weakly but significantly correlated with preceding and following expired volume. It is concluded that some control strategies typical of qui et breathing contribute to volume variability in speech breathing.