Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States; Auditory Research Center, Health Research Association, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, 1640 Marengo Street Suite 326, Los Angeles, CA 90033, United States.
Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States; Auditory Research Center, Health Research Association, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, 1640 Marengo Street Suite 326, Los Angeles, CA 90033, United States.
Hear Res. 2022 Oct;424:108583. doi: 10.1016/j.heares.2022.108583. Epub 2022 Jul 22.
In the auditory system, frequency is represented as tonotopic and temporal response properties of the auditory nerve. While these response properties are inextricably linked in normal hearing, cochlear implants can separately excite tonotopic location and temporal synchrony using different electrodes and stimulation rates, respectively. This separation allows for the investigation of the contributions of tonotopic and temporal cues for frequency discrimination. The present study examines frequency discrimination in adult cochlear implant users as conveyed by electrode position and stimulation rate, separately and combined. The working hypothesis is that frequency discrimination is better provided by place and rate cues combined compared to either cue alone. This hypothesis was tested in two experiments. In the first experiment, frequency discrimination needed for melodic contour identification was measured for frequencies near 100, 200, and 400 Hz using frequency allocation modeled after clinical processors. In the second experiment, frequency discrimination for pitch ranking was measured for frequencies between 100 and 1600 Hz using an experimental frequency allocation designed to provide better access to place cues. The results of both experiments indicate that frequency discrimination is better with place and rate cues combined than with either cue alone. These results clarify how signal processing for cochlear implants could better encode frequency into place and rate of electrical stimulation. Further, the results provide insight into the contributions of place and rate cues for pitch.
在听觉系统中，频率表现为听觉神经的音位和时间响应特性。虽然这些响应特性在正常听力中是不可分割的，但耳蜗植入物可以分别使用不同的电极和刺激率来分别激发音位位置和时间同步性。这种分离允许研究音位和时间线索对频率分辨的贡献。本研究通过电极位置和刺激率分别和组合来检查成年耳蜗植入使用者的频率分辨能力。工作假设是，与单独使用任何一种线索相比，组合使用位置和率线索可以更好地提供频率分辨。该假设在两个实验中进行了检验。在第一个实验中，使用类似于临床处理器的频率分配模型，测量了在 100、200 和 400 Hz 附近用于旋律轮廓识别的频率分辨力。在第二个实验中，使用旨在更好地利用位置线索的实验频率分配来测量 100 到 1600 Hz 之间的音高排序的频率分辨力。两个实验的结果都表明，与单独使用任何一种线索相比，组合使用位置和率线索可以更好地进行频率分辨。这些结果阐明了耳蜗植入物的信号处理如何将频率更好地编码为电刺激的位置和速率。此外，这些结果为音高的位置和率线索的贡献提供了深入了解。
