Application of gammachirp filter banks to simulate the auditory cochlea mechanism of hearing impaired people
Date Issued
2007
Date
2007
Author(s)
Lin, Yu-Chieh
DOI
zh-TW
Abstract
As far as hearing-impaired people is considered, they might encounter the difficulties in the process of learning and communication due to not able to perceive the complete signal of sounds in the correct way, which leads normal people have misunderstanding and wrong perception towards hearing-impaired people. If normal people without hearing problems can sense or really hear the voices or sounds which hearing-impaired people actually receive by means of certain instrument or tool, we can truly understand and realize such inconveniences of life and learning process for hearing-impaired people; moreover we can assist to improve their lives by solving the problems caused by hearing impairment.
The cochlea plays a very important and critical role of analysis of signal of sounds in entire hearing system. Since the basilar membrane inside cochlea reacts different responses on amplitudes and frequency of the signal of sounds, its function works as one band pass filter bank. The high frequency of sound causes bigger response to the base of cochlea; on the contrary, the low frequency of sound results in bigger response to the apex of cochlea. The research objective is to explore that each point of the basilar membrane inside cochlea has its property of the band pass filter bank while shows in the frequency responses to voice wave, since each point has its characteristic frequency. In accordance of the principle of digital band pass filter bank, we specifically design the parallel connection of band pass filter bank, and the band pass filter bank respectively utilize one-third-octave and critical band as the method to divide the band, which is to simulate the selectivity of the cochlea towards the frequency intensity. In another hand, the filter bank of gammatone and of gammachirp, published and designed by the cochlea measurement experiment consistent of physical and psychological auditory mechanism, will be used to simulate the auditory cochlea mechanism of the inner cochlea. Then, the outer ear, middle ear will be connected with the filter bank of gammatone and of gammachirp by the way of cascade connection to simulate the peripheral auditory system and mechanism of outer ear, middle ear and inner ear altogether.
In this research, four different types of filter banks will be designed to test the signal of sounds, which can verify and prove whether these filter banks can really function and be consistent of the properties of frequency selectivity of the cochlea. Accordingly we can design different hearing loss filter banks in accordance with the different level of hearing loss. When the signal of sounds passes through filter banks, we can simulate and imitate the signal of sounds which hearing impaired people actually receive. Through such a devise, the normal people can actually hear this type of sounds; they can really understand when they put themselves in people’s shoes. We hope that we can really understand and realize their difficulties and inconveniences which they have to face everyday by this experience; then we can further assist them and help them to improve their lives and make their lives better and easier.
Subjects
耳蝸
帶通濾波器組
基底膜
珈瑪調
珈瑪啁啾
cochlea
band pass filter bank
basilar membrane
gammatone
gammachirp
Type
thesis