Vocal Resonance Alterations Following Anterior Palatoplasty and Expansion Sphincter Pharyngoplasty

This study aims to examine the effects of combined anterior palatoplasty (AP) and expansion sphincter pharyngoplasty (ESP) on vocal resonance and nasalization in patients with mild to moderate obstructive sleep apnea syndrome (OSAS), utilizing objective testing methods.

A total of 28 patients with mild to moderate OSAS, determined by polysomnography, were included in the study. Preoperative assessments and postoperative evaluations at the 1st and 6th months were conducted, during which patients produced steady sustained phonation of the vowels /ɑ/, /ɛ/, /ɯ/, /i/, /ɔ/, /œ/, /u/, and /y/. Formant frequencies (F0, F1, F2, F3, and F4) were analyzed. Additionally, nasalization was evaluated using the vowel /ɑ/ in the syllable /ɟ ɑ ɟ/ and quantified by analyzing F0, F1, F2, F3, F4, and A1P0 values, where A1 represents the amplitude of the first formant harmonic peak and P0 represents the amplitude of the lowest nasal peak.

No statistically significant changes were observed in the fundamental frequency (F0) of any vowels before and after surgery. At 6 months postoperatively, significant decreases in F1 for /ɑ/ (P = 0.047) and F3 for /u/ (P = 0.017) were noted. Nasalization measurements at 6 months showed significant changes, including a decrease in F3 (P = 0.023), an increase in F4 (P = 0.025), and a decrease in A1P0 values for nasalized /ɑ/ (P = 0.013).

AP + ESP affect vocal resonance specifically in back vowels (/ɑ/, /u/), and leads to nasalization, consistent with the surgical focus on the velopharyngeal region, while preserving fundamental frequency across all vowels. These alterations might influence how individuals perceive their voice, possibly having particular relevance for professional voice users.