Aerodynamic and Laryngeal Characteristics of Place-Dependent Voice Onset Time Differences.

OBJECTIVE: To investigate aerodynamic and laryngeal factors associated with place-dependent voice onset time (VOT) differences.

METHODS: The speech materials were /p∧, t∧, k∧/, each produced 15 times by 10 adult English speakers in the carrier phrase "say __ again". The sound pressure level was targeted within a ±3 dB range. Intraoral air pressure (Po) was obtained using a buccal-sulcus approach. VOT, Po, maximum Po declination rate (MPDR), duration of the laryngeal devoicing gesture (LDG), occlusion duration, and the duration of the Po drop to baseline (atmosphere) to the onset of voicing (PDOV) were determined for each stop.

RESULTS: VOT was longer for the alveolar and velar stops compared to the bilabial stop. A constant LDG was observed for all stops regardless of place of articulation. Occlusion duration, however, was significantly shorter for the alveolar and velar stops compared to the bilabial stop. Aerodynamically, Po was greatest for the velar stop, intermediate for the alveolar stop, and smallest for the bilabial stop. MPDR index showed a slower rate of Po drop for the velar and alveolar stops compared with the bilabial stop. PDOV was found to be longer for /p/ than /t/ and /k/.

CONCLUSION: Findings provide empirical evidence for the inter-related roles of Po, rate of Po change, and laryngeal factors in place-dependent variations of VOT.