The role of the laryngeal collar in vocal tract acoustics

Wim G. J. Ritzerfeld, M.Sc., Donald G. Miller, M.Mus, Ph.D, and
Harm K. Schutte, M.D., Ph.D.

Groningen Voice Research Lab. University of Groningen, Ant. Deusinglaan 1,
NL 9713 AV, Groningen, The Netherlands

In "Acoustic Interpretation of Resonant Voice", Titze has presented a theory stating that the vibrational movements of the vocal folds can be reinforced by vocal tract resonance (2001). In order for this reinforcement to take place, vocal tract impedance needs to have a positive phase angle. In other words, the supraglottic pressure wave needs to be pulled forward in time with respect to the glottal air flow wave. Titze presented calculations indicating that this favourable condition is enhanced when: the passage to the pharynx from the vestibulum via the laryngeal collar is narrow.
In the present study, experiments were carried out that were aimed at investigating the above theory empirically. Two subjects produced several phonations, which were simultaneously measured by a pressure transducer located inside the laryngeal collar, just above the vocal folds, an electroglottograph, and a microphone placed in front of the subject. Results were established that support the conclusion that just above the vocal folds the acoustical wave shows the theoretically desired phase shift.

Titze, I. R. (2001). Acoustic interpretation of resonant voice. Journal of Voice, 15, 519-528.

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