Koichi Omori, MD, Myojo Kanaji, MD, Hisayoshi Kojima, MD

This paper investigates laryngeal adjustments in producing voiceless consonants in running speech. High-speed videofiberscopy (1,000 frames per second) of vocal fold vibration and manometry of intrapharyngeal pressure were simultaneously undertaken during running speech of Japanese sentences containing /p/, /t/, /k/, /s/, and /sh/ by 4 normal volunteers. During the production of voiceless plosives, vocal fold vibration stopped with a spindle-shaped glottal opening after the increase of intrapharyngeal pressure (3.9 to 4.4 cm H20); however, the vocal folds did not abduct. During the production of voiceless fricatives, vocal fold vibration stopped after vocal fold abduction with a V-shaped glottal opening followed by the increase of intrapharyngeal pressure. These results suggest that glottal opening in producing voiceless plosives was passively induced by intrapharyngeal pressure, whereas glottal opening in producing voiceless fricatives may be controlled by adjustments of the laryngeal muscles. This study may present 2 different mechanisms of glottal opening in producing voiceless consonants.