Effects of auditory feedback deprivation on non-native French vowels produced by children with cochlear implants

Abstract

The objective of the present study was to examine alternative explanations for changes in speech demonstrated by individuals with a cochlear implant, in response to auditory feedback deprivation. By employing French vowels, for which monolingual English speakers do not have internal representations, this study compared formant frequencies of vowels produced in the presence and absence of auditory feedback. It was hypothesized that the lack of auditory feedback should not lead to vowel formant frequency shifts for these novel sounds. However, if, in addition to formants frequency shifts, increases in speaking rate and fundamental frequencies are observed in the absence of auditory feedback, the data would support the idea that talkers attempt to speak more clearly to maximize information from other sensory channels. Four children with cochlear implants (7–11 years of age) and four children with normal hearing (mean age 8.6 years) repeated English (familiar) and French (unfamiliar) vowels presented through a loudspeaker. In addition, the CI children repeated the syllables with the processor turned off for approximately 0.95–1.5 s before repeating each syllable. Formant frequencies, fundamental frequency and vowel durations were estimated from the vowels. Results showed that while there were some differences between children with CI and NH with respect to English vowels, there were no outstanding differences with respect to French vowels. Further, the results of the study showed formant frequency shifts in addition to increases in vowel durations and fundamental frequency in the absence of auditory feedback. While preliminary, the findings support the notion that talkers may attempt to speak clearly in the absence of auditory feedback, to attain information about their speech through other sensory channels. Future studies are necessary to confirm and extend these findings with a larger group of talkers.

• auditory feedback
• cochlear implants
• children
• speech production
• French vowels