Deroche Mickael L D, Kulkarni Aditya M, Christensen Julie A, Limb Charles J, Chatterjee Monita
Centre for Research on Brain, Language and Music, McGill University Montreal, QC, Canada.
Auditory Prostheses and Perception Laboratory, Boys Town National Research Hospital Omaha, NE, USA.
Front Neurosci. 2016 Mar 3;10:73. doi: 10.3389/fnins.2016.00073. eCollection 2016.
Sensitivity to static changes in pitch has been shown to be poorer in school-aged children wearing cochlear implants (CIs) than children with normal hearing (NH), but it is unclear whether this is also the case for dynamic changes in pitch. Yet, dynamically changing pitch has considerable ecological relevance in terms of natural speech, particularly aspects such as intonation, emotion, or lexical tone information. Twenty one children with NH and 23 children wearing a CI participated in this study, along with 18 NH adults and 6 CI adults for comparison. Listeners with CIs used their clinically assigned settings with envelope-based coding strategies. Percent correct was measured in one- or three-interval two-alternative forced choice tasks, for the direction or discrimination of harmonic complexes based on a linearly rising or falling fundamental frequency. Sweep rates were adjusted per subject, in a logarithmic scale, so as to cover the full extent of the psychometric function. Data for up- and down-sweeps were fitted separately, using a maximum-likelihood technique. Fits were similar for up- and down-sweeps in the discrimination task, but diverged in the direction task because psychometric functions for down-sweeps were very shallow. Hits and false alarms were then converted into d' and beta values, from which a threshold was extracted at a d' of 0.77. Thresholds were very consistent between the two tasks and considerably higher (worse) for CI listeners than for their NH peers. Thresholds were also higher for children than adults. Factors such as age at implantation, age at profound hearing loss, and duration of CI experience did not play any major role in this sensitivity. Thresholds of dynamic pitch sensitivity (in either task) also correlated with thresholds for static pitch sensitivity and with performance in tasks related to speech prosody.
研究表明，佩戴人工耳蜗（CI）的学龄儿童对音高静态变化的敏感度低于听力正常（NH）的儿童，但目前尚不清楚对于音高动态变化情况是否也是如此。然而，在自然语音方面，动态变化的音高具有相当重要的生态学意义，尤其是在语调、情感或词汇声调信息等方面。21名听力正常的儿童、23名佩戴人工耳蜗的儿童，以及18名听力正常的成年人和6名佩戴人工耳蜗的成年人参与了本研究，以供比较。佩戴人工耳蜗的受试者使用基于包络编码策略的临床指定设置。在一间隔或三间隔二选一强制选择任务中，根据线性上升或下降的基频来判断谐波复合体的方向或进行辨别，测量正确百分比。扫描速率根据受试者进行对数尺度调整，以覆盖心理测量函数的整个范围。使用最大似然技术分别拟合上扫和下扫的数据。在辨别任务中，上扫和下扫的拟合相似，但在方向任务中有所不同，因为下扫的心理测量函数非常平缓。然后将命中和误报转换为d'和β值，并在d'为0.77时提取阈值。两个任务的阈值非常一致，佩戴人工耳蜗的受试者的阈值比听力正常的同龄人高得多（更差）。儿童的阈值也高于成年人。植入年龄、重度听力损失年龄和人工耳蜗使用时长等因素在这种敏感度方面没有起到任何主要作用。动态音高敏感度的阈值（在任何一项任务中）也与静态音高敏感度的阈值以及与语音韵律相关任务的表现相关。
