Holt Colleen M, Lee Kathy Y S, Dowell Richard C, Vogel Adam P
Audiology and Speech Pathology, The University of Melbourne, Victoria, Australia.
Office of the Associate Pro-Vice Chancellor, Coursework, College of Science, Health and Engineering, La Trobe University, Victoria, Australia.
J Speech Lang Hear Res. 2018 Jan 22;61(1):174-185. doi: 10.1044/2017_JSLHR-H-17-0027.
The purpose of this study is to assess Cantonese word recognition and the discrimination of Cantonese tones with manipulated contours by child and adolescent cochlear implant (CI) users and a group of peers with normal hearing (NH). It was hypothesized that the CI users would perform more poorly than their counterparts with NH in both tasks and that CI users implanted before 2 years of age would perform better than those implanted after 2 years.
Forty-one participants were recruited from hospitals, schools, and kindergartens in Hong Kong: Ten CI users implanted at or before 2 years of age ("early" CI group), 13 CI users implanted after 2 years of age ("late" CI group), and 18 individuals with NH. The mean age at implantation of the early CI group was 1.5 years (SD = 0.3), and for the late CI group, it was 4.3 years (SD = 2.1). Participants were a mean of 13.3 years of age (SD = 3.7) at time of testing. Participants completed a Cantonese word recognition test and a discrimination task using Cantonese tones with modified fundamental frequency trajectories.
Both CI user groups obtained significantly lower scores than the group with NH on the word recognition test. Mean percent correct scores for the word recognition test were 79% for the early CI group, 69% for the late CI group, and 97% for the group with NH. The group with NH consistently achieved higher scores than the CI user groups when discriminating manipulated Cantonese tones. Increasing the acoustic difference between tones improved discrimination performance for CI users for level tone contrasts only. CI users implanted at or before 2 years of age obtained higher scores than those implanted later.
The results of this study add further evidence that children using CIs do not perform as well as peers in perceiving Cantonese tones. Modification of tones to increase pitch range did not consistently improve the ability of children with implants to perceive the difference between tones. Further research is required to fully assess potential benefits of early implantation for speakers of tonal languages.
本研究旨在评估儿童和青少年人工耳蜗（CI）使用者以及一组听力正常（NH）的同龄人对粤语单词的识别能力，以及对经过轮廓处理的粤语声调的辨别能力。研究假设是，在这两项任务中，人工耳蜗使用者的表现会比听力正常的同龄人更差，并且2岁之前植入人工耳蜗的使用者会比2岁之后植入的使用者表现更好。
从香港的医院、学校和幼儿园招募了41名参与者：10名在2岁及之前植入人工耳蜗的使用者（“早期”人工耳蜗组），13名在2岁之后植入人工耳蜗的使用者（“晚期”人工耳蜗组），以及18名听力正常的个体。早期人工耳蜗组的平均植入年龄为1.5岁（标准差=0.3），晚期人工耳蜗组为4.3岁（标准差=2.1）。测试时参与者的平均年龄为13.3岁（标准差=3.7）。参与者完成了一项粤语单词识别测试和一项使用具有修改后的基频轨迹的粤语声调的辨别任务。
在单词识别测试中，两个人工耳蜗使用者组的得分均显著低于听力正常组。单词识别测试的平均正确百分比得分，早期人工耳蜗组为79%，晚期人工耳蜗组为69%，听力正常组为97%。在辨别经过处理的粤语声调时，听力正常组的得分始终高于人工耳蜗使用者组。仅对于平调对比，增加声调之间的声学差异可提高人工耳蜗使用者的辨别性能。2岁及之前植入人工耳蜗的使用者得分高于之后植入的使用者。
本研究结果进一步证明，使用人工耳蜗的儿童在感知粤语声调方面的表现不如同龄人。修改声调以增加音高范围并不能始终提高植入人工耳蜗儿童感知声调差异的能力。需要进一步研究以全面评估早期植入对声调语言使用者的潜在益处。
