Laryngeal adjustments in the production of consonant clusters and geminates in American English

The glottal opening gesture and its timing control in various sequences of voiceless obstruents were investigated by the combined techniques of electromyography, photo-electric glottography, and fiberoptic endoscopy. The results obtained at both electromyographic and movement levels revealed that the glottal opening gesture is characterized by a one-, two-, or more-than-two-peaked pattern in a regular fashion according to the phonetic nature of the voiceless segments: each voiceless obstruent or geminate accompanied by aspiration or frication noise tends to require a single separate peak of the opening gesture, while an unaspirated stop embedded in a voiceless environment can be produced within the opening gesture attributed to an adjacent aspirated stop or fricative. Such an independent opening gesture of the glottis for the production of voiceless aspirated stops or voiceless fricatives even in sequentially unvoiced contexts can be interpreted as assuring the aerodynamic requirements for turbulent noise production during the aspirated stop or fricative segment.