Effect of Jaw Opening on the Speech and Voice of Normal-Hearing and Hearing-Impaired Children: An Acoustic and Physiological Study

Abstract

This study utilises instrumental measures to examine the effect of jaw opening on the speech and voice of normal-hearing and hearing-impaired (HI) children. The simultaneous recording system employed consisted of acoustic recording, electroglotography (EGG), and a marker-based facial tracking device. Participants, aged between 9 and 12 years, included nine normal hearing children (4 females and 5 males) and six children with hearing impairments (3 females and 3 males). Participants were instructed to say the standard word list used for the Goldman-Fristoe Test of Articulation and a list of words including each of the vowels /i/, /a/, and /u/, preceded by the consonants /b/, /g/, or /s/ in a CV, CVC or CVCV context. In total, the second word list included 45 words (3 vowels X 3 consonants X 5 trials) and participants were asked to repeat a second time using an open jaw posture. Measures of the acoustic signals included: frequencies of formants one and two (F1, F2), fundamental frequency (F0), percent jitter, percent shimmer, signal-to-noise ratio (SNR), vowel length, consonant length, and spectral moments (M1 and M2). Vowel spaces, derived from F1 and F2, were also analysed. The EGG measures included fundamental frequency, open quotient, and speed quotient. The marker-based facial tracking signals was analyzed to derive the measure of maximum jaw displacement. Individual participants’ measures were submitted to a series of two-way Analysis of Variances (ANOVAs) and the average data for participants in the normal-hearing group to a series of twoway repeated measures ANOVAs. Results showed that increased jaw opening led to an increase in vowel area (as shown by the F1/F2 plots of the vowels /i/, /a/ and /u/). A significant decrease in SNR was also found for many participants in the open jaw condition, indicating increase vocal stability. The HI participants showed smaller vowel areas than their normal-hearing peers. These results suggest the utility of increase jaw opening may increase vowel area and voice quality for both HI and normal-hearing children.