Producing Nasal Vowels Without Nasalization? Perceptual Judgments and Acoustic Measurements of Nasal/Oral Vowels Produced by Children With Cochlear Implants and Typically Hearing Peers.

Abstract

Purpose: The objective of the present study is to investigate nasal and oral vowel production in French-speaking children with cochlear implants (CIs) and children with typical hearing (TH). Vowel nasality relies primarily on acoustic cues that may be less effectively transmitted by the implant. The study investigates how children with CIs manage to produce these segments in French, a language with contrastive vowel nasalization.

Method: The children performed a task in which they repeated sentences containing a consonant-vowel-consonant-vowel-type pseudoword, the vowel being a nasal or oral vowel from French. Thirteen children with CIs and 25 children with TH completed the task. Among the children with CIs, the level of exposure to Cued Speech (CS) was either occasional (CS-) or intense (CS+). The productions were analyzed through perceptual judgments and acoustic measurements. Different acoustic cues related to nasality were collected: segmental durations, formant values, and predicted values of nasalization. Multiple regression analyses were conducted to examine which acoustic features are associated with perceived nasality in perceptual judgments.

Results: The perceptual judgments realized on the children's speech productions indicate that children with sustained exposure to CS (CS+) exhibited the best identified and most distinct oral/nasal productions. Acoustic measures revealed different production profiles among the groups: Children in the CS+ group seem to differentiate between nasal and oral vowels by relying on segmental duration cues and variations in oropharyngeal configurations (associated with formant differences) but less through nasal resonance.

Conclusion: The study highlights (a) a benefit of sustained CS practice for CI children for the intelligibility of nasal-oral segments, (b) privileged exploitation of temporal (segmental duration) and salient acoustic cues (oropharyngeal configuration) in the CS+ group, and (c) difficulties among children with CI in distinguishing nasal-oral segments through nasal resonance.

Supplemental material: https://doi.org/10.23641/asha.27744768.