Theoretic investigations of the "source-filter" model have indicated a pronounced acoustic interaction of glottal source and vocal tract. Empirical investigations of formant pattern variations apart from changes in vowel identity have demonstrated a direct relationship between the fundamental frequency and the patterns. As a consequence of both findings, independence of phonation and articulation may be limited in the speech process. Within the present study, possible interdependence of phonation and phoneme was investigated: vocal fold vibrations and larynx position for vocalizations of different vowels in a healthy man and woman were examined by high-speed light-intensified digital imaging. We found 1) different movements of the vocal folds for vocalizations of different vowel identities within one speaker and at similar fundamental frequency, and 2) constant larynx position within vocalization of one vowel identity, but different positions for vocalizations of different vowel identities. A possible relationship between the vocal fold vibrations and the phoneme is discussed.
