Effects of Class III malocclusion on young male adults' vocal tract development: a pilot study

Abstract

Purpose: To compare the vocal tract configuration between male speakers with Class III malocclusion and their normally developing counterparts and to investigate the concomitant acoustic changes caused by the alterations in vocal tract configuration.

Patients and methods: Eight young male patients with Class III malocclusion and 8 normally developing counterparts participated in this study. Acoustic reflection technology was used to measure vocal tract dimensions in the 2 groups. A continuous speech sample and 4 sustained vowels (/a/, /æ/, /i/, and /u/) were recorded from each participant to obtain the fundamental frequency and the first 3 formant frequencies (F1, F2, and F3).

Results: The results showed significantly greater oral length and oral volume for young male patients with Class III malocclusion than their cohorts. The F1 of vowel /u/ was found to be significantly higher in male patients with Class III malocclusion than their cohorts. The vowel space of the 4 recorded vowels was reduced and the F1-F2 formant map for /u/ was relatively more scattered in male patients with Class III malocclusion than in the control speakers.

Conclusion: This study has provided preliminary information on the effects of Class III malocclusion on vocal tract configuration and concomitant acoustic changes in young male patients.