Superior lateral pharyngeal wall movements in speech

Area of Science:

• Speech Science
• Acoustic Phonetics
• Physiology of Speech Production

Background:

• The velopharyngeal port (VPP) regulates airflow between the nasal and oral cavities during speech.
• Lateral pharyngeal wall (LPW) movements contribute to VPP closure, particularly for nasal consonants.
• Vowel context is known to influence articulatory gestures, but its specific effect on LPW movement requires detailed investigation.

Purpose of the Study:

• To investigate the influence of adjacent vowels (/a/ vs. /u/) on medial movements of the lateral pharyngeal wall.
• To analyze the impact of vowel context on the amplitude, duration, and timing of velopharyngeal port gestures.
• To examine the relationship between vowel identity and the coordination of velum and lateral pharyngeal wall function.

Main Methods:

• Utilized a computerized ultrasound system to record medial movements of the lateral pharyngeal wall.
• Subjects produced Consonant-Vowel-Nasal-Vowel-Consonant (CVNVC) sequences with all combinations of /a/, /u/, /n/, and /m/.
• Analyzed opening (CVN) and closing (NVC) gestures for movement amplitude, duration, and onset time.

Main Results:

• The amplitude of both VPP opening and closing gestures by the LPW was significantly reduced in the context of the vowel /u/ compared to /a/.
• The onset timing of the LPW opening gesture toward the nasal consonant was influenced by both the preceding and succeeding vowels.
• These findings indicate differential vowel effects on the motor control of velopharyngeal function.

Conclusions:

• Vowel identity plays a crucial role in modulating the magnitude and timing of lateral pharyngeal wall movements during speech.
• The observed reduction in LPW movement with the vowel /u/ suggests context-dependent adjustments in velopharyngeal control strategies.
• Understanding these functional couplings is essential for a comprehensive model of speech production and potential speech disorder interventions.