McKay Colette M, Henshall Katherine R
The University of Melbourne, Department of Otolaryngology, 384-388 Albert St., Vic 3002, East Melbourne, Australia.
Hear Res. 2003 Jul;181(1-2):94-9. doi: 10.1016/s0378-5955(03)00177-1.
The most common current pulse shape used for cochlear implants is a biphasic rectangular pulse. The interphase gap (IPG) is the duration of the zero-current portion which lies between the two phases. It is known from single-nerve studies in animals that, as the IPG decreases, the biphasic pulse becomes less efficient in activating the nerve cell. Thus, it can be predicted that stimulation using smaller IPGs will necessitate the use of higher currents to maintain the loudness required by the cochlear implantee. The development of contemporary processing schemes commonly involves the maximization of the rate parameter, and to achieve this in sequential pulsatile stimulation, the IPG as well as the pulse phase duration must be minimized. This experiment investigated the effect of IPG on loudness in eight cochlear implantees who use the CI24 implant manufactured by Cochlear Ltd. An exponential increase in current level was required to maintain equal loudness when IPG is reduced from 100 to 45 and 8.4 micros. The effect of IPG was greater at lower levels, was greater for shorter pulse durations (26 micros compared to 52 micros), and was not significantly different for the rates (1 kHz or 4 kHz) tested.
目前用于人工耳蜗的最常见电流脉冲形状是双相矩形脉冲。相间间隙（IPG）是两个相位之间零电流部分的持续时间。从动物单神经研究中可知，随着IPG减小，双相脉冲激活神经细胞的效率会降低。因此，可以预测，使用较小的IPG进行刺激将需要使用更高的电流来维持人工耳蜗使用者所需的响度。当代处理方案的发展通常涉及速率参数的最大化，而在顺序脉冲刺激中要实现这一点，IPG以及脉冲相位持续时间都必须最小化。本实验研究了IPG对8名使用科利耳有限公司生产的CI24植入体的人工耳蜗使用者响度的影响。当IPG从100微秒降至45微秒和8.4微秒时，需要指数级增加电流水平才能维持相同响度。IPG的影响在较低水平时更大，在较短脉冲持续时间（26微秒与52微秒相比）时更大，并且在所测试的速率（1千赫或4千赫）下没有显著差异。
