Research And Application On Music Perception Simulation Of Cochlear Implant

The basic principle of cochlear implant is converting acoustic signals into electrical stimulation, stimulating the auditory nerve on ear basement membrane corresponding to different ear perception frequency and help patients restore hearing loss in auditory perception. With the deep development of the cochlear implant (or CI) technique, cochlear implants acquire the simple sound to understanding the speech information step by step, further hope to perceive more comprehensive and melodious sound world.Time coding theory and location coding theory are the perceive theories in CI perception. In the perception process of cochlear implant, electrode stimulation rate is related to time coding, and the number and arrangement of electrodes is mainly about position encoding. Researchers have been trying to improve stimulation rate to solve the problem caused by time coding, but the problems caused by location coding should be solved by changing the number of electrodes and electrodes arrangement.The current assessment results of cochlear implant show that cochlear implant users have better speech perception in a quiet environment, but the perception of music signal is worse. In the paper the basic reason of the different perception for speech signals and music is given form the signal analysis aspect. The major different in speech signal and music signal is the distribution of the spectral energy, the spectral energy of speech is mainly distributed on several speech frequencies and the respective harmonic partials, but for music, the spectral energy is distributed over the musical note fundamental frequency and its harmonic partials. In words, music is more complex and richer, the current electrode arrangement is not enough to completely pass all of the music features.To explore the mechanism of cochlear implant music perception, some simulation experiments is designed to study the effect of harmonic components for musical notes and melody. CIS coding strategy algorithm based on FFT is used in simulation experiments. According to different experiments, some participants are invited to participate in the listening test. And the experimental results show that the distribution of the harmonic components is very important for music perception, especially for timbre perception for some instruments which have the obvious characteristics in spectrum envelope, such as clarinet.Finally, this paper puts forward some schemes to improve the music perception of cochlear implant. On the one hand, encoding strategy should be added into more fine structure information, on the other hand, more electrodes should be applied, and the electrodes arrangement should be changed. Moreover, photoacoustic effect has begun to be applied to the artificial cochlear implant currently, using optical fiber laser to induce hearing may be the cochlear development a new direction in the future.