School of Foreign Studies, Nanjing University of Science and Technology, China.
Research Centre for Language, Cognition, and Neuroscience, Department of Chinese and Bilingual Studies, The Hong Kong Polytechnic University.
J Speech Lang Hear Res. 2022 Aug 17;65(8):2789-2800. doi: 10.1044/2022_JSLHR-21-00584. Epub 2022 Jul 22.
This study aims to investigate the different degeneration processes of categorical perception (CP) of Mandarin lexical tones in the normal aging population and the pathological aging population with mild cognitive impairment (MCI).
In Experiment I, we compared the identification and discrimination of Tone 1 and Tone 2 across young adults, seniors aged 60-65 years, and older seniors aged 75-80 years with normal cognitive abilities. In Experiment II, we compared lexical tone identification and discrimination across young adults, healthy seniors, and age-matched seniors with MCI.
In Experiment I, tone perception was intact in seniors aged below 65 years. Those aged above 75 years could also maintain normal tone identification, whereas they showed poorer tone discrimination correlated with age-related poorer hearing level. In Experiment II, healthy seniors showed normal CP of Mandarin tones. Tone identification was also normal in those with MCI, whereas their tone discrimination had significantly degenerated.
In the normal aging population, age-related hearing loss decreased signal audibility, accounting for poorer discrimination of Mandarin lexical tones in seniors above 75 years. In the pathological aging population with MCI, the poorer discrimination of lexical tones may be attributed to the additive effect of age, hearing loss, and cognitive impairment (e.g., impaired working memory and long-term phonological memory). This study uncovered the roles of low-level sensory processing and high-level cognitive processing in lexical tone perception in the Chinese aging population.
本研究旨在探讨正常衰老人群和伴有轻度认知障碍（MCI）的病理性衰老人群中，普通话声调范畴知觉（CP）的不同退化过程。
在实验 1 中，我们比较了年轻成年人、60-65 岁的老年人和认知能力正常的 75-80 岁的高龄老年人对 Tone1 和 Tone2 的识别和辨别能力。在实验 2 中，我们比较了年轻成年人、健康老年人和年龄匹配的伴有 MCI 的老年人对普通话声调的识别和辨别能力。
在实验 1 中，65 岁以下的老年人的声调感知完好。75 岁以上的老年人仍能保持正常的声调识别，而他们的声调辨别能力则与年龄相关的听力水平下降有关。在实验 2 中，健康老年人表现出正常的普通话 CP。伴有 MCI 的老年人的声调识别也正常，但其声调辨别能力显著下降。
在正常衰老人群中，与年龄相关的听力损失降低了信号的可听度，导致 75 岁以上老年人对普通话声调的辨别能力下降。在伴有 MCI 的病理性衰老人群中，声调辨别能力的下降可能归因于年龄、听力损失和认知障碍（如工作记忆和长时音韵记忆受损）的附加效应。本研究揭示了低水平感觉处理和高水平认知处理在汉语衰老人群中对声调感知的作用。
