Intraglottal Aerodynamics at Vocal Fold Vibration Onset

Area of Science:

• Acoustic phonetics
• Bioacoustics
• Speech science

Background:

• The soft onset is the most common physiological voice start in spontaneous speech.
• It involves airflow through a narrow glottis, leading to initial vocal fold oscillations.
• Understanding these transient events is key to analyzing voice production.

Purpose of the Study:

• To analyze the intraglottal mechanical events during physiological soft voice onset.
• To investigate the role of turbulence and pressure dynamics in initiating vocal fold oscillation.

Main Methods:

• Combined in vivo measurements of airflow, glottal area, and pressure.
• Analysis of transient mechanical events during soft onset.
• Calculation of Reynolds number to identify turbulence onset.

Main Results:

• The first vocal fold oscillation coincides with the appearance of turbulence (critical Reynolds number).
• Turbulence acts as a trigger for the vocal fold and vocal tract oscillator.
• Initial oscillations are sinusoidal, with balanced lung and Bernoulli pressures.

Conclusions:

• Turbulence is identified as the trigger for physiological soft voice onset.
• The mechanical properties of the vocal folds and vocal tract determine oscillation frequency.
• The interplay of pressures and airflow dynamics governs the initiation of phonation.