A Study on an Cochlear Implant System with a Reverse Solution of a Model for the Peripheral Auditory System

一种声音（也包括并考虑环境声）被有效地转化为人工耳蜗20个通道的电极脉冲。为此，扩展语音编码系统常用的多脉冲语音编码算法，在时频空间中计算最佳解，确定耳蜗基底膜上的最佳脉冲位置（时间轴上）和电极位置（频率轴上）。通过对优化准则问题的重新审视，采用波形和频谱最小二乘误差准则的方法取得了较好的效果。基于电极脉冲刺激下听神经放电模式的生理实验模型，建立了声学模拟系统。这可以执行一个精确的声学模拟现在从电极刺激信号。采用外周听觉系统生理模型的反向过程，在听神经的放电模式中再现了更多的输入声信号。考虑到从神经递质数量上恢复基底膜振动的非线性反向模型的各种限制条件，建立了“反向听觉模型”，以便再现无失真的输入声音。植入人工耳蜗的人能听到什么“声音”？果不其然，“声音模拟”考虑到我们想要获得是否与人工耳蜗植入者听到的“声音”相对应这个问题的某种关键，并详细采访了滨松医学院数十名植入者。结果，下面的事情就明白了。在声学模拟中，模仿接近于植入人工耳蜗的瞬间的“声音”。然后，人工耳蜗植入者学习得很快（不到几分钟）。只要他们相信，几个月后就能听到。也许人们在记忆中与听过一次的“声音”有关。在声学模拟中，虽然由于信号组成的技术问题，经常会出现声音失真和噪声混叠的情况，但很明显，这对人工耳蜗来说是完全无关的问题。因此，可以这样说，对人工耳蜗声音的音质评估不能被误认为在声学模拟时产生了不必要的失真。少

A sound (environmental sound is also included and considered) is efficiently changed into the electrode pulses of 20 channels of a cochlear implant. For this purpose, expanding an algorithm of the multi-pulse voice coding usually used by the voice coding system, it was going to calculate the optimum solution in a time-frequency space to determine the optimum pulse position (on a time-axis) and the electrode position (on a frequency-axis) along the basilar-membrane in a cochlea. As a result of looking over the problem of an optimization criterion again, good results were obtained by the method of the minimum-squared-error criterion of waveform and spectrum.The acoustic simulation system based on the physiology experiment model of the auditory-nerve firing pattern by electrode pulse stimulus was created. This can perform an accurate acoustic simulation now from an electrode stimulus signal.The reverse process of the physiology model of a peripheral auditory system was followed, and the a … More coustic signal of an input was reproduced from the firing pattern of an auditory nerve. The "reverse hearing model" was created so that input sound with no distortion might be reproduced, in consideration of various restriction conditions of the nonlinear reverse model that restores basilar-membrane vibration from quantity of a nerve transmitter.What "sound" do cochlear implantees hear? Sure enough, the "sound simulation" considered that we wanted to obtain a certain key to the question whether it corresponds to the "sound" which is hearing a cochlear implantee, and interviewed in detail dozens of people who have implanted at the Hamamatsu medical college. As a result, the following thing was understood. Imitating in an acoustic simulation is close to "sound" of the moment of the hookup to a cochlear implant. Then, a cochlear implantee has learned quickly (less than to several minutes). It becomes audible as before after several months as far as they believe. Perhaps people relates with the "sound" in ones memory that was being listened to once.In the acoustic simulation, although the distortion of sound and mixing of noise often happened for the sake of the technical problem on signal composition, it became clear that it is entirely an unrelated problem for a cochlear implantee. Therefore, it can be said that tone-quality evaluation of cochlear-implant sound must not be mistaken by having produced an unnecessary distortion at the time of an acoustic simulation. Less