Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, United States of America.
Auditory Research Center, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America.
PLoS One. 2020 Dec 3;15(12):e0242842. doi: 10.1371/journal.pone.0242842. eCollection 2020.
Cochlear implant users hear pitch evoked by stimulation rate, but discrimination diminishes for rates above 300 Hz. This upper limit on rate pitch is surprising given the remarkable and specialized ability of the auditory nerve to respond synchronously to stimulation rates at least as high as 3 kHz and arguably as high as 10 kHz. Sensitivity to stimulation rate as a pitch cue varies widely across cochlear implant users and can be improved with training. The present study examines individual differences and perceptual learning of stimulation rate as a cue for pitch ranking. Adult cochlear implant users participated in electrode psychophysics that involved testing once per week for three weeks. Stimulation pulse rate discrimination was measured in bipolar and monopolar configurations for apical and basal electrodes. Base stimulation rates between 100 and 800 Hz were examined. Individual differences were quantified using psychophysically derived metrics of spatial tuning and temporal integration. This study examined distribution of measures across subjects, predictive power of psychophysically derived metrics of spatial tuning and temporal integration, and the effect of training on rate discrimination thresholds. Psychophysical metrics of spatial tuning and temporal integration were not predictive of stimulation rate discrimination, but discrimination thresholds improved at lower frequencies with training. Since most clinical devices do not use variable stimulation rates, it is unknown to what extent recipients may learn to use stimulation rate cues if provided in a clear and consistent manner.
人工耳蜗使用者可以通过刺激率来感知音高，但当刺激率高于 300Hz 时，辨别力会下降。鉴于听觉神经具有显著而特殊的同步响应刺激率的能力，至少可以响应高达 3kHz 的刺激率，甚至可以响应高达 10kHz 的刺激率，这种对高刺激率的限制令人惊讶。作为音高线索的刺激率敏感性在人工耳蜗使用者中差异很大，通过训练可以提高。本研究考察了刺激率作为音高排序线索的个体差异和感知学习。成年人工耳蜗使用者参与了电极心理物理学测试，每周测试一次，持续三周。在双极和单极配置下，对顶端和基端电极进行了刺激脉冲率辨别测试。检查了 100-800Hz 的基刺激率。使用空间调谐和时间整合的心理物理衍生度量标准来量化个体差异。本研究考察了跨受试者的测量分布、空间调谐和时间整合的心理物理衍生度量标准的预测能力，以及训练对率辨别阈值的影响。空间调谐和时间整合的心理物理度量标准不能预测刺激率辨别，但随着训练，低频的辨别阈值会提高。由于大多数临床设备不使用可变刺激率，因此，如果以清晰一致的方式提供刺激率线索，受话器是否可以学习使用这些线索尚不清楚。
