Design Of Electronic Speech Processing Machine For Cochlear Implants

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, Cochlear Implant is a device that restores partial hearing of profoundly deaf people. Its basic principle is that extracting important speech information and coding them and exciting the deaf's cochlear hearing neuroma with weak direct current pulse, then making the deaf restore hearing.This paper based on the DSP technology and the speech signal processing theory, has conducted the system research to the artificial electronic Cochlear Implant speech signal processing and made use of DSP to realize software and hardware system. This paper mainly has conducted more thorough research from following several aspects:In the speech processing aspect, the paper took the sense of hearing system, hearing mechanism and spoken language coding scheme as a foundation, has chosen speech signal processing theory-spectrum peak (SPEAK) theory as the method to be realize in this paper, and proposed one kind of improved speech signal processing method based on short-time fourier transform(STFT), the method greatly enhanced the speech processing speed and could carry on the flexible division according to deafness patients hair cell and the residual nerve to the speech channels, it has overcome the SPEAK method insufficiently flexible flaw.In hardware design aspect, we used the power loss low DSP chip as the speech signal processor, it overcome the special purpose integrated circuit's flaw of designing and improvement complex, so that might act according to the different patient's situation to use the different speech processing method and had no change in hardware electric circuit structure, the way reduced the development cost and cycle.In software design aspect, in order to enhance the system timeliness and the stability and reduces the difficulty which software designs, embedded real-time operating systemμC/OS-II has been transplanted in this system, and carried on the multitasks programming according to the speech processing method in this system.μC/OS-II could manage and dispatch tasks flexibly, it fully made up DSP's insufficiency in the control.The system could collect speech signal, and filter the signal into twenty-two contiguous frequency bands, then extracted envelopes of bandpassed waveforms, coded and eventually send it out. 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.