Department of English Language and Literature, Hong Kong Baptist University, Kowloon Tong.
Unit of Human Communication, Development, and Information Sciences, University of Hong Kong, Pokfulam.
J Speech Lang Hear Res. 2022 Jul 18;65(7):2554-2570. doi: 10.1044/2022_JSLHR-21-00276. Epub 2022 Jul 12.
Evidence increasingly indicates that people with developmental stuttering have auditory perception deficits. Our previous research has indicated similar but slower performance in categorical perception of the speech sounds under the quiet condition in children who stutter and adults who stutter (AWS) compared with their typically fluent counterparts. We hypothesized that the quiet condition may not be sufficiently sensitive to reveal subtle perceptual deficiencies in people who stutter. This study examined this hypothesis by testing the categorical perception of speech and nonspeech sounds under backward masking condition (i.e., a noise was presented immediately after the target stimuli).
Fifteen Cantonese-speaking AWS and 15 adults who do not stutter (AWNS) were tested on the categorical perception of four stimulus continua, namely, consonant varying in voice onset time (VOT), vowel, lexical tone, and nonspeech, under the backward masking condition using identification and discrimination tasks.
AWS demonstrated a broader boundary width than AWNS in the identification task. AWS also exhibited a worse performance than AWNS in the discrimination of between-category stimuli but a comparable performance in the discrimination of within-category stimuli, indicating reduced sensitivity to sounds that belonged to different phonemic categories among AWS. Moreover, AWS showed similar patterns of impaired categorical perception across the four stimulus types, although the boundary location on the VOT continuum occurred at an earlier point in AWS than in AWNS.
The findings provide robust evidence that AWS exhibit impaired categorical perception of speech and nonspeech sounds under the backward masking condition. Temporal processing (i.e., VOT manipulation), frequency/spectral/formant processing (i.e., lexical tone or vowel manipulations), and nonlinguistic pitch processing were all found to be impaired in AWS. Altogether, the findings support the hypothesis that AWS might be less efficient in accessing the phonemic representations when exposed to a demanding listening condition.
越来越多的证据表明，有发育性口吃的人存在听觉感知缺陷。我们之前的研究表明，与他们的典型流利者相比，口吃的儿童和成人（AWS）在安静条件下对言语声音的范畴知觉表现出类似但较慢的表现。我们假设安静条件可能不足以揭示口吃者的细微感知缺陷。本研究通过测试在反向掩蔽条件下的言语和非言语声音的范畴知觉来检验这一假设（即，在目标刺激后立即呈现噪声）。
15 名讲粤语的 AWS 和 15 名不口吃的成年人（AWNS）在反向掩蔽条件下使用识别和辨别任务，对四个刺激连续体的范畴知觉进行了测试，即，声门起始时间（VOT）变化的辅音、元音、词汇音调和非言语声音。
AWS 在识别任务中表现出比 AWNS 更宽的边界宽度。AWS 在辨别跨类别刺激方面的表现也比 AWNS 差，但在辨别类别内刺激方面的表现相当，这表明 AWS 对属于不同音位类别的声音的敏感性降低。此外，AWS 在四个刺激类型中表现出相似的受损范畴知觉模式，尽管在 AWS 中，VOT 连续体上的边界位置比在 AWNS 中更早。
这些发现提供了有力的证据，表明 AWS 在反向掩蔽条件下表现出言语和非言语声音的受损范畴知觉。AWS 表现出在时间处理（即 VOT 操作）、频率/频谱/共振峰处理（即词汇音或元音操作）和非语言音高处理方面的受损。总的来说，这些发现支持了这样一种假设，即在面临苛刻的听力条件时，AWS 可能在访问音位表示方面效率较低。
