Artifacts Reduction In Electrically Evoked Auditory Brainstem Responses And The Application On Interaural Electrode Pairing For Bilateral Cochlear Implants

A cochlear implant(CI) is an electrical device that helps to restore hearing to the profoundly deaf. At present, bilateral implantation is one of the cochlear implantation. Bilateral cochlear implants have provided some success in improving spatial hearing abilities to bilateral CI users. But the matching degree between the electrodes in the cochlea directly affects the performance of the cochlear implant. The existing electrode pairing method s mainly based on an interaural comparison of pitch perception and the interaural paring time difference(IPTD). These two methods need according to the patient’s feedback to evaluate the performance binaural cochlear. They do not apply to those who cannot give feedback. At the same time, the interaction between the ears should be obtained by recorded and processed the electrically auditory brainstem response(EABR) signals of the cochlear implant patients. EABR signal usually contains a variety of artifacts, especially facial nerve stimulation(FNS) artifacts, which lead to the serious distortion of the EABR signal. At present, there is no reliable method can remove the FNS artifacts. In order to improve the matching degree of bilateral cochlear implants, more simple and objective methods for interaural electrode pairing and effective ways for FNS artifacts Reduction of EABR signal shoud be developed. The main researches are as follows:(1) In order to get the real EABR signals, analysis based on independent component(ICA) is proposed to deal with facial nerve artifacts in EABR signals. The real amplitude of the waveform V in EABR signal is closer to 2μv.(2) a objective method based on binaural interaction component(BIC) was proposed to for the electrodes paring of the cochlear implant. BIC is obtained by using the processed EABR signals. In order to get the feasibility of BIC for the electrode pairing, a ll results based on interaural comparison of pitch perception and IPTD and BIC are compared. The methods of pitch perception and IPTD need feedback, they’re too subjective.(3) The system for EABR signal processing is build in the study, independent component analysis(ICA) is carried out to remove the artifacts of EABR signals. and the interaction component(BIC) for electrode paring is tested.The results show that the IC A method can e ffectively remove the facial nerve artifacts in EABR signals. The binaural interaction component from EABR signals is used for the electrode pairing, the results of BIC are basically the same with the previous methods’ results, which demonstrate the objective method of binaural interaction components for the electrode pairing is feasible.