Acoustic Characteristics of Speech Sounds in Normal Hearing Children of Deaf Parents

Objectives: The acoustic-phonetic characteristics of a hearing-impaired person's speech differ from those of a hearing person's speech. Despite their normal hearing abilities, children of hearing impaired parents may have different speech patterns from children of normal hearing parents because of the differing speech stimuli they receive from their parents. We studied the acoustic-phonetic characteristics of the vowels and stop consonants produced by the normal hearing children of deaf parents to reveal how the speech of deaf parents affect their children's speech sounds. Methods: Normal hearing children of ages 3 to 6, nine of deaf parents and nine of normal hearing parents, were included in the study. The first formants (F1) and second formants (F2) of vowels /i/, /u/, /a/ and vowel triangle area as well as the voice onset times and closure durations in CV and CVC of stops between two groups were compared. Results: F1s and F2s of all vowels except F2 of /i/ were not significantly different between two groups. However, the vowel triangle area of normal hearing children of deaf parents was significantly larger than that of children of normal hearing parents. The VOTs in all stops except /p*/ in VC were not significantly different between two groups. Similarly, the closure durations in all stops were not significantly different between two groups. Conclusion: Normal hearing children of deaf parents show normal development of speech sound acquisition; however, hearing-impairment of parents might affect their children's speech acquisition to some degree.