Use of F2 ratio to discriminate between hearing-impaired and non-hearing impaired children

Formant frequencies change as a function of the movements of the articulators and as a function of changes in the configuration of the vocal tract. Subjects with hearing loss produce vowels using a limited vertical range and reduce the arc of the tongue, leading to vowel formant centralization. The current study compared F2 ratio and formant frequencies to discriminate children with different levels of hearing loss. Recordings of the speech of 40 children ranging in age from 7 to 9 years diagnosed with hearing loss (moderate, moderate-to-severe, severe, profound) and 40 children with normal hearing were acoustically analyzed. The task was vowel production and the words read contained the vowels /a/, /i/, /u/. The audio files were transferred to PRAAT software (version 13.3.5) to record their formant frequencies. The same vowel formant elements were used to construct the F2i/F2u ratios. Data from F1a, F1i, F1u and F2u in groups with normal hearing and hearing loss did not show significant differences. The F2i/F2u ratio (normal-moderate: p = 0.017, normal-moderate-to-severe: p = 0.003, normal-severe: p = 0.000, normal-profound: p = 0.000), F2a (normal-moderate: p = 0.031, normal-moderate-to-severe: p = 0.015, normal-severe: p = 0.023, normal-profound: p = 0.000) and F2i (normal-moderate: p = 0.005, normal-moderate-to-severe: p = 0.000, normal-severe: p = 0.000, normal-profound: p = 0.000) showed significant differences between the normal hearing and hearing loss groups for all levels. The level F2i/F2u ratio performed consistently, but levels F2a and F2i showed decreased performance. The F2i/F2u ratio was more appropriate for determining vowel production in normal hearing and hearing loss groups.