The Study On Speech Signal Processing Of Cochlear Implant Based On DSP

Hearing is an important medium for people to acquire information from others and exchange information with others. But deafness is one of the most common illnesses in handicapped. As we know, the profoundly deaf patient cannot resort to the hearing aid device, however, through cochlear implant, such an effective way, it is completely possible for them to restore hearing. The foreign advanced products have got high resolution of speech signal, and bring a lot of benefit for the deaf patients. But in our country, the deaf patients cannot benefit from the high technology, just because they cannot afford the high it. So, we should develop the cochlear implant system depending on ourselves, and we should improve its quality and lower its price to meet the requirement of deaf patients in our country, which can lead to great social benefit and economic benefit.This paper gives systemic study on speech signal processing of cochlear implant based on DSP technology and speech signal processing theory, and perform the speech signal processing by DSP. The systemic block diagram of cochlear implant speech signal processing is presented, and the core part of the system is digital signal processor chip-TMS320LF2407, and gives detail introduction and design to each part of this system. The continuous interleave sampling (CIS) is adopted to process speech signal, and wavelet transform (WT) is used in the CIS method. Finally, this paper introduces a computer-based acoustic simulation method to simulate actual sound perception by the deaf patient fitted with cochlear implants. The experiment result shows that the synthesis speech signal is similar to the original speech signal in its frequency envelope, which indicates that CIS speech signal processing method includes envelope signal and frequency signal of original speech, so deaf people can restore some hearing in this way. In the study of this project, there are some features:(1). DSP technology is used to process speech signal of cochlear implant, and can realize the fast, real-time processing of speech signal.(2). After the analysis and comparison of the different speech signal processing methods, the continuous interleave sampling (CIS) is chose to process speech signal, and wave transform is used in the CIS method.(3). Due to its difficulty to test actual sound perception by the deaf patient fitted with cochlear implants by physiological experiment, this paper introduces acomputer-based acoustic simulation method to simulate actual sound perception by the deaf patient fitted with cochlear implants, so the result of CIS processing can be validated.This paper can provide some use of reference for developing some high quality and low price cochlear implant, which can bring a lot of benefits to deaf patients in our country...