Syllable-related breathing in infants in the second year of life

This study explored whether breathing behaviors of infants within the 2nd year of life differ between tidal breathing and breathing supporting single unarticulated syllables and canonical/articulated syllables.

Vocalizations and breathing kinematics of 9 infants between 53 and 90 weeks of age were recorded. A strict selection protocol was used to identify analyzable breath cycles. Syllables were categorized on the basis of consensus coding. Inspiratory and expiratory durations, excursions, and slopes were calculated for the 3 breath cycle types and were normalized using mean tidal breath measures.

Tidal breathing cycles were significantly different from syllable-related cycles on all breathing measures. There were no significant differences between unarticulated syllable cycles and canonical syllable cycles, even after controlling for utterance duration and sound pressure level.

Infants in the 2nd year of life exhibit clear differences between tidal breathing and speech-related breathing, but categorically distinct breath support for syllable types with varying articulatory demands was not evident in the present findings. Speech development introduces increasingly complex utterances, so older infants may produce detectable articulation-related adaptations of breathing kinematics. For younger infants, breath support may vary systematically among utterance types, due more to phonatory variations than to articulatory demands.