Production of nasal vowels in children with CI (Fagniart et al., 2024)

<b>Purpose: </b>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.<b>Method: </b>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.<b>Results: </b>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.<b>Conclusion: </b>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.<b>Supplemental Material S1.</b> Tables containing all the information concerning the statistical models performed and the fixed-effects power analyses described in the Results section.Fagniart, S., Delvaux, V., Harmegnies, B., Huberlant, A., Huet, K., Piccaluga, M., Watterman, I., &amp; Charlier, B. (2024). Producing nasal vowels without nasalization? Perceptual judgments and acoustic measurements of nasal/oral vowels produced by children with cochlear implants and typically hearing peers. <i>Journal of Speech, Language, and Hearing Research</i>. Advance online publication. https://doi.org/10.1044/2024_JSLHR-24-00083

研究目的：本研究旨在探究法语母语的人工耳蜗植入（Cochlear Implants, CIs）儿童与典型听力（Typical Hearing, TH）儿童的鼻化元音与非鼻化元音产出表现。元音鼻音化主要依赖声学线索，而这类线索经人工耳蜗传递的效果往往欠佳。本研究聚焦法语这一存在元音鼻音对立的语言，旨在探明人工耳蜗植入儿童如何产出此类音段。
研究方法：受试儿童完成一项朗读任务，需重复包含辅音-元音-辅音-元音结构假词的句子，其中的元音为法语鼻化元音或非鼻化元音。本研究共纳入13名人工耳蜗植入儿童与25名典型听力儿童。其中人工耳蜗植入儿童又根据唇读辅助手势（Cued Speech, CS）的接触时长分为两组：偶尔接触组（CS−）与高频接触组（CS+）。研究通过感知判断与声学测量两种方式对语音产出进行分析，采集了与鼻音化相关的多项声学指标：音段时长、共振峰数值，以及鼻音化预测值。随后开展多元回归分析，以探究感知判断中与感知鼻音化相关的声学特征。
研究结果：对受试儿童语音产出的感知判断结果显示，长期接触唇读辅助手势的高频接触组（CS+）儿童，其鼻化与非鼻化元音的辨识度最高、区分度最强。声学测量结果则揭示了不同组别间的产出差异：CS+组儿童似乎主要通过音段时长与口咽构型变化（对应共振峰差异）来区分鼻化与非鼻化元音，而非通过鼻腔共鸣。
研究结论：本研究明确了三点发现：（1）长期练习唇读辅助手势可提升人工耳蜗植入儿童对鼻化-非鼻化音段的辨识度；（2）CS+组儿童更倾向于利用时域（音段时长）与显著声学线索（口咽构型）完成元音区分；（3）人工耳蜗植入儿童在通过鼻腔共鸣区分鼻化与非鼻化元音时存在困难。
补充材料S1：包含本研究结果部分提及的所有统计模型与固定效应效力分析相关信息的表格。
Fagniart, S., Delvaux, V., Harmegnies, B., Huberlant, A., Huet, K., Piccaluga, M., Watterman, I., 与 Charlier, B. (2024). 无鼻音化时如何产出鼻化元音？人工耳蜗植入儿童与典型听力同龄人的鼻化/非鼻化元音产出的感知判断与声学测量. 《言语、语言与听力研究期刊》. 提前在线发表. https://doi.org/10.1044/2024_JSLHR-24-00083