Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, USA.
Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, New York, USA.
Ear Hear. 2024;45(2):441-450. doi: 10.1097/AUD.0000000000001440. Epub 2023 Nov 13.
Individuals with cochlear implants (CIs) often report that listening requires high levels of effort. Listening effort can increase with decreasing spectral resolution, which occurs when listening with a CI, and can also increase with age. What is not clear is whether these factors interact; older CI listeners potentially experience even higher listening effort with greater signal degradation than younger CI listeners. This study used pupillometry as a physiological index of listening effort to examine whether age, spectral resolution, and their interaction affect listening effort in a simulation of CI listening.
Fifteen younger normal-hearing listeners (ages 18 to 31 years) and 15 older normal-hearing listeners (ages 65 to 75 years) participated in this experiment; they had normal hearing thresholds from 0.25 to 4 kHz. Participants repeated sentences presented in quiet that were either unprocessed or vocoded, simulating CI listening. Stimuli frequency spectra were limited to below 4 kHz (to control for effects of age-related high-frequency hearing loss), and spectral resolution was decreased by decreasing the number of vocoder channels, with 32-, 16-, and 8-channel conditions. Behavioral speech recognition scores and pupil dilation were recorded during this task. In addition, cognitive measures of working memory and processing speed were obtained to examine if individual differences in these measures predicted changes in pupil dilation.
For trials where the sentence was recalled correctly, there was a significant interaction between age and spectral resolution, with significantly greater pupil dilation in the older normal-hearing listeners for the 8- and 32-channel vocoded conditions. Cognitive measures did not predict pupil dilation.
There was a significant interaction between age and spectral resolution, such that older listeners appear to exert relatively higher listening effort than younger listeners when the signal is highly degraded, with the largest effects observed in the eight-channel condition. The clinical implication is that older listeners may be at higher risk for increased listening effort with a CI.
人工耳蜗植入者（CI）常报告称，聆听需要付出很高的努力。在使用 CI 聆听时，频谱分辨率降低会导致聆听努力增加，而且随着年龄的增长，聆听努力也会增加。目前尚不清楚这些因素是否相互作用；与年轻的 CI 使用者相比，年龄较大的 CI 使用者在信号退化程度更大的情况下，可能会经历更高的聆听努力。本研究使用瞳孔测量法作为聆听努力的生理指标，以检查年龄、频谱分辨率及其相互作用是否会影响 CI 聆听模拟中的聆听努力。
本实验共有 15 名年轻正常听力者（年龄 18 至 31 岁）和 15 名年长正常听力者（年龄 65 至 75 岁）参与；他们的听力阈值在 0.25 至 4 kHz 之间正常。参与者在安静环境下重复听到的句子，这些句子未经处理或语音编码，模拟 CI 聆听。刺激频谱限于 4 kHz 以下（以控制与年龄相关的高频听力损失的影响），通过减少语音编码通道的数量来降低频谱分辨率，分别为 32 通道、16 通道和 8 通道条件。在完成任务的过程中记录了言语识别得分和瞳孔扩张。此外，还获得了认知测量，包括工作记忆和处理速度，以检查这些测量值的个体差异是否预测瞳孔扩张的变化。
在正确回忆句子的试验中，年龄和频谱分辨率之间存在显著的交互作用，在 8 通道和 32 通道语音编码条件下，年长正常听力者的瞳孔扩张更为明显。认知测量无法预测瞳孔扩张。
年龄和频谱分辨率之间存在显著的交互作用，因此，在信号严重退化的情况下，年龄较大的听众似乎比年龄较小的听众付出更多的聆听努力，在 8 通道条件下观察到的影响最大。临床意义是，年龄较大的听众在使用 CI 时可能会面临更高的聆听努力风险。
