In Vivo Quantification of the Intraglottal Pressure: Modal Phonation and Voice Onset

Area of Science:

• Acoustics
• Biomechanics
• Physiology

Background:

• Intraglottal pressure drives vocal fold vibration, essential for phonation.
• Direct measurement of intraglottal pressure is challenging and can disrupt natural voicing.
• Existing methods rely on indirect computation using transglottal flow and glottal area.

Purpose of the Study:

• To compute intraglottal pressure during the vocal fold vibratory cycle.
• To analyze the pressure dynamics during sustained modal phonation and soft voice onset.
• To investigate the role of glottal duct shape, air compressibility, and vocal tract inertance.

Main Methods:

• Utilized in vivo measured transglottal flow and glottal area.
• Applied Bernoulli's energy law and vocal tract inertance principles for computation.
• Performed calculations for both convergent and divergent glottal duct shapes with absolute calibration.

Main Results:

• Integrated intraglottal pressure during the opening phase consistently exceeds that during the closing phase, regardless of glottal duct shape.
• The airflow curve's rightward skew relative to the glottal area curve is key, driven by air compressibility and vocal tract inertance.
• During soft voice onset, pressure differences increase, and the pressure wave's phase lead over glottal opening progressively advances.

Conclusions:

• The findings confirm the fundamental condition for sustained vocal fold oscillation.
• Air compressibility and vocal tract inertance explain the observed pressure dynamics and phase shifts.
• The study provides a method for quantifying intraglottal pressure, aiding phonation research.