在實作出一個初步模擬聽損耳蝸的模型之後，未來的研究方向可以分為四個，以下分 別說明之。
1. 加入更多聽損現象，使模型更趨完整
由於聽損現象都是彼此相關的，因此如果沒有考慮周到的話，在實際比較病患的聽損 程度以及模擬的聽損程度時，量測結果可能被這些沒有考慮到的因素左右，因此造成我們 在調整參數時有程度過少或程度過多的現象；因此我們可以參考〔55〕中提到的有關時域 封包模糊化的現象，或是學者針對其它聽損現象所做的研究，再加入一些參數到我們的模 型中。
2. 建立符合各種不同聽損患者的個人化模型
為了達到以上的目的，因此我們必頇要有聽損患者加入研究才行；如此一來，不但可 以讓我們驗證演算法的效果，也有助於參數的選定，舉例如下：
測量不同聽損患者的聽損程度，並根據測量結果調整模型參數後，讓聽損患者以及正 常人分別以原始語料、經處理語料做聽力測詴，並比較兩組數據間的相似程度。
不僅僅只是測量語句可辨別度之間的相似性，還可以針對語音品質做調整；例如在 5.3 節當中討論到的，用迭代方式產生載波的合成方法，會比用白高斯雜訊濾波得到載波 的合成方法，有較好的語音品質；然而這些語音品質都是正常人的感覺，並不能代表 聽損患者聽到的聲音，因此透過聽損患者，我們可以進一步加強語音品質，使得經過 此系統的聲音能更接近聽損患者聽到的聲音。
3. 幫助助聽器的演算法的發展
Moore 圑隊在〔15-16〕中，不只驗證了響度聚集、最小可聽水平提升、以及分頻解析 度降低對於辨識率會有影響，也加入了 NAL prescription 來驗證該模型是否能反應出 NAL 的特性—根據不同頻帶的響度衰減程度，加上適當的增益，來補償因為最小可聽水平提升 造成的聽力損失。
我們可以先參考 Moore 團隊的做法，將 NAL 加入我們的模型之中，觀察是否會得到 相似的結果；接著再進一步以經過實際測詴，確實有助於聽覺濾波器變寬的患者聽力的助 聽器演算法〔24〕，或者是其它公認有幫助的助聽器演算法，來驗證我們的模型是否可以 反應出這些演算法的特性。在經過各種聽損現象的助聽器演算法的測詴，並証實我們的演 算法確實有效果之後，我們就可以用這套系統來評估發展助聽器演算法了。
4. 發展補償分頻解析度降低的助聽器演算法
如同在緒論中提到的，我們特別注重分頻解析度降低的聽損現象，因此也期望發展出 能夠補償此現象造成的聽力損失的演算法；除了參考第四章中所提到的未來方向之外，我 們也可以參考〔56〕的有關頻譜銳化（spectral sharpening）的想法，並搭配我們發展出的 聽損耳蝸模型，加以延伸應用來解決頻譜模糊化的問題。
參考文獻
[1] D. Byrne, and H. Dillon, ―The National Acoustic Laboratories'(NAL) new procedure for selecting the gain and frequency response of a hearing aid,‖ Ear Hear., 7, pp. 257-265., 1986.
[2] E. Villchur, ―Simulation of the effect of recruitment on loudness relationships in speech,‖ J.
Acoust. Soc. Am., 56, pp. 1601-1611, 1974.
[3] P. J. Fitzgibbons, and F. L. Wightman, ―Gap detection in normal and hearing-impaired listeners,‖ J. Acoust. Soc. Am., 72, pp. 761-765, 1982.
[4] R. S. Tyler, A. Q. Summerfield, E. J. Wood, and M. A. Fernandes, ―Psychoacoustic and phonetic temporal processing in normal and hearing-impaired listeners,‖ J. Acoust. Soc.
Am., 72, pp. 740-752, 1982.
[5] B. R. Glasberg, B. C. J. Moore, and S. P. Bacon, ―Gap detection and masking in hearing-impaired and normal-hearing subjects,‖ J. Acoust. Soc. Am., 81, pp. 1546-1556., 1987.
[6] B. R. Glasberg, and B. C. J. Moore, ―Effects of envelopeee fluctuations on gap detection,‖
Hear. Res., 64, pp. 81-92., 1992.
[7] G. Pick, E. F. Evans, and J. P. Wilson, ―Frequency resolution in patients with hearing loss of cochlear origin,‖ in Psychophysics and Physiology of Hearing, edited by E. F. Evans and J.
P. Wilson (Academic, London), 1977.
[8] M. Florentine, S. Buus, B. Scharf, and E. Zwicker, ―Frequency selectivity in
1980.
[9] R. S. Tyler, J. W. Hall, B. R. Glasberg, B. C. J. Moore, and R. D. Patterson, ―Auditory filter asymmetry in the hearing impaired,‖ J. Acoust. Soc. Am., 76, pp. 1363-1368, 1984.
[10] B. R. Glasberg, and B. C. J. Moore, ―Auditory filter shapes in subjects with unilateral and bilateral cochlear impairments,‖ J. Acoust. Soc. Am., 79, pp. 1020-1033, 1986.
[11] B. C. J. Moore, and B. R. Glasberg, ―Comparisons of frequency selectivity in simultaneous and forward masking for subjects with unilateral cochlear impairments,‖ J. Acoust. Soc.
Am., 80, pp. 93-107, 1986.
[12] R. S. Tyler, ―Frequency resolution in hearing-impaired listeners,‖ in Frequency Selectivity in Hearing, edited by B. C. J. Moore, (Academic, London), 1986.
[13] M. Li, H. G. McAllister and N. D. Black, ―Multirate Modeling of Human Ear Frequency Resolution for Hearing Aids,‖ Digital Signal Processing Workshop Proceedings (IEEE), pp.
157-160, 1996.
[14] T. Baer, and B. C. J. Moore, ‗‗Effects of spectral smearing on the intelligibility of sentences in the presence of noise,‘‘ J. Acoust. Soc. Am., 94, pp. 1229–1241, 1993.
[15] B. C. J. Moore, and B. R. Glasberg, ‗‗Simulation of the effects of loudness recruitment and threshold elevation on the intelligibility of speech in quiet and in a background of speech,‘‘
J. Acoust. Soc. Am., 94, pp. 2050–2062, 1993.
[16] Y. Nejime and B. C. J. Moore, ―Simulation of the effect of threshold elevation and loudness recruitment combined with reduced frequency selectivity on the intelligibility of speech in noise,‖ J. Acoust. Soc. Am., 102, pp. 603-615, 1997.
[17] H. M. Hu, J. Q. Sang, M. Lutman, S. Bleeck, ―Simulation of hearing loss using compressive gammachirp auditory filters,‖ ICASSP, pp. 22-27, 2011.
[18] P.M. Sellick, R. Patuzzi, and B. M. Johnstone, ―Measurement of basilar membrane motion in the guinea pig using the Mössbauer technique,‖ J. Acoust. Soc. Am., 72, pp. 131-141, 1982.
[19] M. A. Ruggero, and N. C. Rich, ―Furosemide alters organ of Corti mechanics: Evidence for feedback of outer hair cells upon the basilar membrane,‖ J. Neurosci, 11, pp. 1057-1067, 1991.
[20] T. S. Chi, class notes of Auditory and Acoustical Information Processing, Department of Communication Engineering, National Chiao-Tung University, Taiwan, 2011.
[21] J. B. Allen, ―Short term spectral analysis, synthesis, and modification by discrete Fourier transform,‖ IEEE-ASSP, 25, pp. 235-238, June 1977.
[22] D. W. Griffin, and J. S. Lim, ―Signal Estimation from Modified Short-Time Fourier Transform,‖ IEEE-ASSP, 32, pp.236-243, 1984.
[23] P. N. Kulkarni, and P. C. Pandey, ―Frequency mapping for multi-band frequency compression for improving speech intelligibility,‖ Proc. 14th National Conference on Communications, pp. 437-441, 2008
[24] P. N. Kulkarni, P. C. Pandey, and D. S. Jangamashetti, ―Multi-band frequency compression for sensorineural hearing impairment,‖ Proc. 16th Int. Conf. Digital Signal Processing, Paper S4P.1., 2009.
[25] T. D. Rossing, The Science of Sound. Reading, MA: Addison-Wesley, 1982.
[26] H. Fletcher, ―Auditory patterns,‖ Rev. Mod. Phys, 12, pp. 47-61, 1940.
[27] E. W. Zwicker, ―Subdivision of audible frequency range into critical bands ( Freqenzgruppen),‖ J. Acoust. Soc. Am., 33(2), pp. 248, 1961.
[28] B. R. Glasberg, and B. C. J. Moore, ―Derivation of auditory filter shapes from notched-noised data,‖ Hear. Res., 47, pp. 103-138, 1990.
[29] H. Fletcher, Speech and Hearing in Communication, 2nd ed., Bell Telephone Laboratories Series, Van Nostrand, Princeton, NJ , 1953.
[30] S. S. Stevens, ―The Measurement of Loudness,‖ J. Acoust. Soc. Am, 27, pp. 815-829, 1955.
[31] A. V. Oppenheim, R. W. Schafer, and J. R. Buck, Discrete-time Signal Processing, 2nd ed., Prentice Hall Signal Processing Series, January 10 1999.
[32] R. E. Cyochicre, ―A weighted overlap-add method of short-time Fourier analysis/synthesis,‖
IEEE-ASSP, 28, pp. 99-102, February 1980.
[33] C. Valens, A Really Friendly Guide to Wavelets.
http://polyvalens.pagesperso-orange.fr/clemens/wavelets/wavelets.html#note1
[34] R. Polikar, The Wavelet Tutorial.
http://person.hst.aau.dk/enk/ST8/wavelet_tutotial.pdf
[35] R. D. Patterson, and A. Cutler, ―Auditory preprocessing and recognition of speech,‖ in Research Directions in Cognitive Science, Vol.I Cognitive Psychology, edited by A.D.
Baddeley and N. O. Bernsen, (Erlbaum, London), 1989.
[36] E. de Boer, and C. Kruidenicr, ―On ringing limits of the auditory periphery,‖ Biol. Cybern., 63, pp. 433-442, 1990.
[37] T. Irino, and R. D. Patterson, ―A Time-Domain, Level-Dependent Auditory Filter: The Gammachirp,‖ JASA, 101, pp. 412-419, 1997.
sounds,‖ JASA, 118, pp. 887-906, August 2005.
[39] G. Kubin, and W. B. Kleijn, ―On speech coding in a perceptual domain,‖ Proc. ICASSP, pp, 205-208, 1999.
[40] B. R. Glasberg, and B. C. Moore, ―Auditory filter shapes in subjects with unilateral and bilateral cochlear impairments,‖ J. Acoust. Soc. Am, 79, pp. 1020–1033, 1986.
[41] B. C. J. Moore, and B. R. Glasberg, ―Comparisons of frequency selectivity in simultaneous and forward masking for subjects with unilateral cochlear impairments,‖ J. Acoust. Soc. Am, 80, pp. 93–107, 1986.
[42] B. C. J. Moore, B. R. Glasberg, and D. A. Vickers, ―Factors influencing loudness perception in people with cochlear hearing loss,‖ in Psychoacoustics, Speech and Hearing Aids, edited by B. Kollmeier, (World Scientific, Singapore), 1996.
[43] R. D. Patterson, and I, Nimmo-Smith, ―Off-frequency listening and auditory-filter asymmetry," J. Acoust. Soc. Am, 67, pp. 229-245, 1980.
[44] R. D. Patterson, I. Nimmo-Smith, D. L. Weber, and R. Milroy, ―The deterioration of hearing with age: frequency selectivity, the critical ratio, the audiogram, and speech threshold,‖ J.
Acoust. Soc. Am, 72, pp. 1788-1803, 1982.
[45] B.C. J. Moore, B. R. Glasberg, R. F. Hess, and J .P. Birchall, ―Effects of flanking noise bands on the rate of growth of loudness of tones in normal and recruiting ears,‖ J. Acoust.
Soc. Am, 77, pp. 1505-1515, 1985.
[46] D.R. Soderquist, and J.W. Lindsey, ―Physiological noise as a masker of low frequencies: the cardiac cycle,‖ J. Acoust. Soc. Am, 52, pp. 1216-1220, 1972.
[47] V. Nedzelnitsky, ―Sound pressures in the basal turn of the cat cochlea,‖ J. Acoust. Soc. Am, 68, pp. 1676-1689, 1980.
[48] T.J. Lynch, V. Nedzelnitsky, and W.T. Peake, ―Input impedance of the cochlea in cat,‖ J.
Acoust. Soc. Am, 72, pp. 108-130, 1982.
[49] J.J. Zwislocki, ―The role of the external and middle ear in sound transmission,‖ In: D.B.
Tower (Ed.), The Nervous System, Vol. 3: Human Communication and its Disorders, Raven Press. New York, 1975.
[50] K. Yasu, K. Kobayashi, K. Shinohara, M. Hishitani, T. Arai, and Y. Murahara, "Frequency compression of critical band for digital hearing aids,‖ in China-Japan Joint Conf. on Acoustics, pp. 159-162, 2002.
[51] Y. T. Kuo, T. J. Lin, Y. T. Lee, W. H. Chang, C. W. Liu, and S. T. Young, ―Design of ANSI S1.11 filterbank for digital hearingaids,‖ in Proc. ICECS, Dec. 2007
[52] D. L. Jones, Quadrature Mirror Filterbanks.
http://cnx.org/content/m12770/1.3/
[53] T. Chi, and S. Shamma, ―Spectrum restoration from multiscale auditory phase singularities by generalized projections,‖ IEEE Transactions on Audio, Speech and Language Processing, vol. 14, no. 4, pp. 1179-1192, July 2006
[54] K.S. Tsai, L. H. Tseng, C. J. Wu, and S. T. Young, ―Development of a Mandarin Monosyllable Recognition Test,‖ Ear and Hearing, 30(1), pp. 90-99, 2009.
[55] R. Drullman, J.M. Festen, and R. Plomp, ―Effect of Temporal Envelope Smearing on Speech Reception,‖ JASA, 95, no. 2, pp. 1053-1064, 1994.
[56] A. Schaub, and P. Straub, ―Spectral sharpening for speech enhancement/noise reduction,‖
Proc. of the International Conference on Acoustics, Speech and Signal Processing, pp.
993-996, 1991.