Acoustic and Aerodynamic Effects of Interarticulator Timing in Voiceless Consonants

Interarticulator timing is a mechanism for producing linguistic contrasts that is widely used in different languages. This paper explores acoustic and aerodynamic effects of variations in laryngeal-oral coordination in voiceless consonants. Measurements of voice onset time and interarticulator phasing for individual tokens of stop consonants show weak correlations, indicating that interarticulator timing is only one factor determining voice onset time. Other factors most likely involved are glottal opening, transglottal pressure and air flow, and vocal fold tension. Taken together, these observations suggest that speakers may only have limited control of voice onset time. This could explain why languages do not seem to make fine-grain use of VOT for linguistic contrasts. Measurements of peak and minimum air flow during individual source pulses, obtained by inverse-filtering oral flow, show a pattern of decrease and increase in vowels following voiceless consonants. Subtle differences in the time course of these patterns occur following different consonants, suggesting that interarticulator phasing may be partly responsible for them. Closer examination reveals consistent correlations with interarticulator phasing for one speaker but inconsistent results for another. The results are discussed in terms of speech motor control and controlled variables in speech.