Summary: Objectives. The objective of this study was to investigate the effects of speaking rate (habitual and
fast) and speech task (reading and spontaneous speech) on seven dependent variables: Breath group size (in syllables),
Breath group duration (in seconds), Lung volume at breath group initiation, Lung volume at breath group
termination, Lung volume excursion for each breath group (in % vital capacity), Lung volume excursion per syllable
(in % vital capacity) and mean speaking Fundamental frequency (fO).
Methods. Ten women and seven men were included as subjects. Lung volume and breathing behaviors were
measured by respiratory inductance plethysmography and fO was measured from audio recordings by the Praat
software. Statistical significance was tested by analysis of variance.
Results. For both reading and spontaneous speech, the group increased mean breath group size and breath group
duration significantly in the fast speaking rate condition. The group significantly decreased lung volume excursion per
syllable in fast speech. Females also showed a significant increase of fO in fast speech. The lung volume levels for initiation
and termination of breath groups, as well as lung volume excursions in % vital capacity, showed great individual
variations and no significant effects of rate. Significant effects of speech task were found for breath group size and lung
volume excursion per syllable, where reading induced more syllables produced per breath group and less % VC spend
per syllable as compared to spontaneous speech. Interaction effects showed that the increases in breath group size and
breath group duration associated with fast rate were significantly larger in reading than in spontaneous speech.
Conclusion. Our data from 17 vocally untrained, healthy subjects showed great individual variations but still
significant group effects regarding increased speaking rate, where the subjects seemed to spend less air per syllable
and inhaled less often as a consequence of greater breath group sizes in fast speech. Subjects showed greater
changes in breath group patterns as a consequence of fast speech in reading than in spontaneous speech, indicating
that effects of speaking rate are dependent on the speech task.