Breathing patterns during spontaneous speech.

Lung volumes, speech intensity, the linguistic location of inspirations, and the variability of each, were studied during spontaneous speech in 6 healthy young women over 7 to 10 sessions each, using respiratory inductance plethysmography. Although average lung volume levels were within the vital capacity range previously reported for speech (Hixon, Goldman, & Mead, 1973), significant inter- and intrasubject variability was observed. This variability was considerable for some subjects (average initiation lung volume varying between 42 and 63% VC over the sessions) and relatively small for others (between 47 and 53% VC). Some of the lung volume variation was associated with changes in mood state, examined by self-report questionnaire at each measurement occasion. Linguistic factors were important influences in the lung volume variation. The majority of breaths in the conversations and monologues preceded structural (clause) boundaries. The volume of air inspired preutterance was found to be linked to the length of the ensuing breath group in each of our 6 subjects, as longer breath groups, spanning up to seven clauses in the spontaneous speech, were anticipated by inspiring to a higher lung volume. The subjects used a comfortable speaking intensity range, which varied for different individuals and sessions over 4 to 18 dB. Increases in speech intensity within individual ranges were not associated with increased lung volumes. The data provide novel insight into associations between physiological and linguistic factors in the control of speech breathing, and are suggestive of the existence of neural planning of the respiratory system, in anticipation of the demands of the utterance.