Biomedical Engineering Study on a Design of Cochlear Implants.

本研究的一个目的是做一个基本的实验，关于一个最佳设计的人工耳蜗，电刺激聋人的生存听觉神经。所进行的研究有以下4点。(1)研究了将电极插入人体耳蜗后，在人体耳蜗内产生什么样的电流分布。(2)在此基础上研制了一种spwwch处理器，并通过植入8通道人工耳蜗评估了人工耳蜗对合成元音的识别能力。(3)开发了一种新型的耳蜗外植入电极，作为一种侵入性较小的耳蜗内植入电极的替代方法。(4)提出了一种单通道识别元音的语音编码方法，并通过动物实验对其有效性进行了评价。结果：(1)刺激电流路径从耳蜗内部到耳蜗外部…More d.研究发现，刺激电流主要在耳蜗外部传播（T.Ifukube, 1987a）。(2)设计了一种具有横向抑制功能的语音处理器，以补偿大电流传播，并通过合成元音识别实验证实了其有效性（T.Ifukube, 1987b）。(3)采用含生理盐水的聚乙烯醇凝胶包覆Pt-Ir丝电极作为单通道耳蜗外植入物的刺激电极。对电极的电特性进行了检查，确定电极具有与人体几乎相同的特性（T.Ifukube, et al, 1988， J.Matsushima et al, 1988）。(4)设计了用于单通道人工耳蜗的语音处理器，该处理器将基音信号与声音的第二共振峰频率相结合，产生时序刺激脉冲。从豚鼠耳蜗对刺激的复合动作电位反应的角度证明了这种编码方法的有效性（T.Ifukube et al ., 1988； K.Takahashi et al ., 1988）。少

A purpose of this research is to do fundamental experiments regarding an optimal design of the cochlear implant that electrically stimulates the survival auditory nerves for the deaf. Researches carried out are the following 4 points.(1)It was investigated what kind of current distribution produces inside the cochlea of a human cadaver when electrodes were inserted into the cochlea. (2) A spwwch processor was developed on the basis of the above result and the discrimination ability of synthetic vowels was evaluated by a subject implanted with an eight channel cochlear prosthesis. (3) A new model of the electrode for the extracochlear implant was developed as a less invasive alternative to electrode insertion in the cochlea. (4) Such a speech coding method that discrimination of vowels is possible with single channel method was proposed and its efficacy was evaluated by an animal experiment.As results, (1) a stimulation current path from the inside of the cochlea to the outside wlarifie … More d. It is found out that a stimulation current spreads largely outside the cochlea (T.Ifukube, 1987a). (2) A speech processor that had a function of lateral inhibition was designed in order to compensate for the wide current spread and its efficacy was confirmed by a recognition experiment of synthesis vowels (T.Ifukube, 1987b). (3)A Pt-Ir wire electrode covered with Polyvinyl alcohol gel including saline solution was developed as a stimulation electrode for a single channel extracochlear implant. The electrical characteristics of the electrode was checked and it was ascertained that the electrode had almost the same characteristics as human body (T.Ifukube, et al, 1988, J.Matsushima et al, 1988). (4) the speech processor for a single channel cochlear implant was designed which produced a time sequential stimulation pulses obtained by combining pitch signals and the second formant frequency of voices. The efficacy of this coding method was proved from a view point of compound action potential responded to stimulation that gave to the cochlea of guinea pig (T.Ifukube et al, 1988, K.Takahashi et al, 1988). Less