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