Bilingual perception of dysarthric speech (Tetzloff et al., 2025)

Purpose: Despite the prevalence of bilingualism, research on the understanding of disordered speech has focused almost exclusively on monolingual populations. Hypothesis-driven studies with dysarthric speech have revealed that greater vocabulary knowledge and working memory support understanding in monolingual listeners. However, whether these explanatory models generalize to bilinguals, who differ in both cognitive and linguistic profiles, is unknown. This study examined whether bilingualism affords a perceptual advantage in understanding dysarthric speech, and whether working memory and vocabulary knowledge contribute to that advantage.Method: Ninety-four listeners, categorized as monolinguals, early bilinguals, or late bilinguals, completed a speech perception task where they transcribed phrases produced by speakers with dysarthria. They also completed working memory and vocabulary assessments.Results: Relative to monolingual and late bilinguals, early bilinguals had equivalent working memory scores, lower vocabulary scores, and reduced intelligibility scores when perceiving dysarthric speech. Vocabulary knowledge, but not working memory, predicted intelligibility scores across all groups. A post hoc correlation analysis within the early bilingual group further revealed that an earlier age of exposure to English was associated with higher intelligibility scores, suggesting that age of language exposure plays a critical role in shaping the linguistic systems that support perception of disordered speech.Conclusions: These findings underscore the importance of vocabulary knowledge and language experience, over working memory, in facilitating understanding of disordered speech. They also highlight the need to refine models of disordered speech perception to account for variability across listener populations, in order to more fully capture the relative contributions of cognitive and linguistic mechanisms.Supplemental Material S1. Number of participants per group by education level.Tetzloff, K. A., Fletcher, A. R., Lansford, K. L., Barrett, T. S., & Borrie, S. A. (2025). Bilingual perception of dysarthric speech. Journal of Speech, Language, and Hearing Research, 68(11), 5278–5291. https://doi.org/10.1044/2025_JSLHR-25-00288

研究目的：尽管双语现象已十分普遍，但现有针对障碍言语理解的研究几乎仅聚焦于单语人群。针对构音障碍言语（dysarthric speech）开展的假说驱动型研究表明，更高的词汇知识水平与工作记忆（working memory）能力可助力单语听者对言语的理解。然而，这些解释模型能否推广至认知与语言特征均存在差异的双语人群，目前尚不明确。本研究旨在探究双语能力是否能为听者理解构音障碍言语带来感知层面的优势，以及工作记忆与词汇知识是否对该优势存在贡献。
研究方法：本研究共招募94名被试，分为单语者、早期双语者与晚期双语者三组，完成一项言语感知任务：对构音障碍者录制的短语进行转录。同时，所有被试均完成工作记忆与词汇知识测评。
研究结果：与单语者及晚期双语者相比，早期双语者的工作记忆评分相当，但词汇知识评分更低，且在感知构音障碍言语时的可懂度评分（intelligibility scores）更低。在所有被试组中，词汇知识可预测可懂度评分，而工作记忆则无此预测作用。对早期双语组开展的事后相关分析（post hoc correlation analysis）进一步显示，更早的英语接触年龄与更高的可懂度评分相关，这表明语言接触年龄在塑造支撑障碍言语感知的语言系统中发挥关键作用。
研究结论：本研究结果强调，相较于工作记忆，词汇知识与语言经验对助力障碍言语理解的重要性更为突出。同时也提示，我们需要优化障碍言语感知模型，以纳入听者群体间的差异，从而更全面地揭示认知与语言机制的相对贡献。
补充材料S1：按受教育水平分组的被试人数。
Tetzloff, K. A., Fletcher, A. R., Lansford, K. L., Barrett, T. S., & Borrie, S. A. (2025). Bilingual perception of dysarthric speech. Journal of Speech, Language, and Hearing Research, 68(11), 5278–5291. https://doi.org/10.1044/2025_JSLHR-25-00288