臺灣博碩士論文加值系統

人工電子耳在1980年代中期就巳經是個商業化的產品了，它的出現為聽障人士開啟了一扇到有聲世界的門，讓他們有機會能夠與其他人溝通，用言語交談，甚至於學習音樂、與正常人過同樣的生活。
雖然人工電子耳巳經是個行之有年的產品了，但不是每個使用者都能夠有很顯著的效果，在一些臨床研究報告中我們發現有些患者聽的很清楚，但是有些卻沒有很明顯的改善，當然這牽涉到許多方面的因素。但臨床研究結果參疵不齊，意味我們在人工電子耳聽覺系統機制的領域上尚有很多可努力的空間。舉例來說：配件的縮小輕便化、刺激策略的改進，電極性能的改良及設計研發…等。
本論文中，我們把焦點放在人工電子耳電極的模擬上，比較不同結構電極的性能：包含平面電極(planar electrode)、球狀電極(sphere electrode)、環狀電極(banded electrode)、半環狀電極(half banded electrode)。同時採用不同的刺激策略：雙極(bipolar mode)、單極(monopolar mode)、同接地(common ground mode)。計算每個電極在不同刺激策略下的電位分佈圖。
接者，我們運用有限元素法模擬出三維(three dimension)的半圈耳蝸模型，同時把不同結構的電極植入至耳蝸模型中，來模擬電極作用(active)時耳蝸裡面所產生的電場，再利用電場值計算出物動函數(activating function)，這樣一來可以得知神經刺激模式(neural excitation pattern)。同時結合以Hodgkin-Huxley方程式為基礎的神經運算模型(GSEF model)模擬出動作電位(action potential)的傳導，也就是說是否能夠刺激神經細胞而產生神經脈衝(spike)，進而傳導至聽覺中央神經系統(central auditory nervous system)。

Cochlear implant(CI) has been appear for many years. It is bring a door for deaf people , Let them have change to communicate with other people，taking to each other. Even learing music and living normal lives.
Since cochlear implant appear in the 1960 years, there are many people to study it. With single channel to multi-chnnel, and improve stimulation strategy, create new design of electrode…etc. Today there are three manufacture in the world　Which produce CI．But we deeply believe there are much space to improve CI performance. i.e. Reduce volume of CI system，　improve speech coding strategies，Studying the performance of electrode.
In this article, we focus on the electrode design, compare the performance within four electrode which have different structure. Planar、Sphere、Banded、Half Banded electrode。And Using different stimulation Strategies to calculate potential distribution which include bipolar monopolar and common ground.Next, we using finite element package to draw cochlear model and implant electrode to cochlear model, and simulate Electric field along cochlear when electrode active. When we get potential value we can calculate activion function(AF). In the mean time we plot AF contour. AF contour plot give a relative indication of spread of neural excitation without calculating the neural response with a nerve fiber model. Neural excitation patterns in the model were determined using the generalized SEF(GSEF) auditory nerve fiber model described by Frijns, de Snoo and Schoonhoven.

第一章 序論…………………………………………………………………………1
1-1 研究背景…………………………………………………………………1
1-2 研究動機與目的…………………………………………………………2
1-3 論文架構…………………………………………………………………5
第二章 聽覺生理與人工電子耳簡介………………………………………………7
2-1 人工電子耳發展歷史……………………………………………………8
2-1-1 人工電子耳與助聽器的差異……………………………………10
2-2 聽覺生理…………………………………………………………………10
2-2-1 聽覺系統簡介……………………………………………………11
2-2-2 聽覺現象…………………………………………………………13
2-3 典型人工電子耳之構造…………………………………………………14
2-4 人工電子耳之植入方式…………………………………………………16
第三章 聲音處理方式及電極之模擬與方析………………………………………18
3-1 聲音的刺激策略…………………………………………………………19
3-2 電場分佈及聽神經刺激模式……………………………………………19
3-3 數值分析方法……………………………………………………………21
3-3-1 有限元素法………………………………………………………21
3-3-2 有限元素法的優點………………………………………………22
3-4 模擬與分析結果…………………………………………………………23
3-4-1 電極的模擬………………………………………………………25
3-5 模擬結果…………………………………………………………………28
第四章 建構耳蝸模型………………………………………………………………38
4-1 有限元素法三維耳蝸模型………………………………………………39
4-2 耳蝸組織特性……………………………………………………………41
第五章 聽神經之刺激模型…………………………………………………………45
5-1 聽神經模型………………………………………………………………45
5-2 GSEF軸索模型……………………………………………………………46
5-3 電位分佈…………………………………………………………………53
5-4 模擬分析結果……………………………………………………………56
第六章 結論…………………………………………………………………………62
參考文獻……………………………………………………………………………64
附錄 ……………………………………………………………………………65

David K. (1993). Fundamentals of engineering electromagnetics. Addison-Wesley Publishing Company, Inc.
Finley, C. C., Wilson, B. S., and White, M. W. (1990). Models of neural responsiveness to electrical stimulation. In Miller, J. M. and Spelman, F. A., Cochlear Implants (pp. 55-96). New York: Springer-Verlag Inc.
Frijns, J. H. M., de Snoo, S. L., and Schoonhoven, R. (1995). Potential distributions and neural excitation patterns in a rotationally symmetric model of the electrically stimulated cochlea. In Frijns, J. H. M., Cochlear Implants. A Modeling Approach(pp. 93-124).
Frijns, J. H. M., Briaire, J. J., and Schoonhoven, R. (2000). Integrated use of volume conduction and neural models to simulate the response to cochlear implants. Simulation Practice and Theory, 8, 75-97.
Girzon, G. (1987). Investigation of current flow in the inner ear during electrical stimulation of intracochlear electrodes. MS Thesis in EE and CS, MIT, Cambridge, Massachusetts.
Hanekom, J. J., (2001). Modeling of the electrode-auditory nerve fiber interface in cochlear prostheses. Ph. D thesis.
Marsh, M. A., Coker N.J., and Jenkins, H. A. (1992). Temporal bone histopathology of a patient with a nucleus 22-channel cochlear implant. The American Journal of Otology, 13, 241-248.
National Institutes of Health(1995). Cochlear implants in adults and children. NIH Consensus Statement. 1-30.
Pickles J. O., (1992). An introduction to the physiology of hearing. Academic Press INC.
Pfingst, B. E,. Morris, D. J., and Miller, A. L. (1995). Effects on electrode configuration on threshold functions for electrical stimulation of the cochlea. Hearing research, 85, 76-84.
Rattay, F. (1990). Electrical nerve stimulation theory, experiments, and application. Novographic, Ing.
Richard, C., Booton, JR. (1992). Computational Methods for electromagnetics and microwaves. (pp.87-101). John Wiley and Sons, Inc.
Suesserman, M. F., and Spelman, F. A. (1993). Lumped-parameter model for in vivo cochlear stimulation. IEEE Transactions on Biomedical Engineering, 40(3), 237-245.