Design Of Comprehensive Detecting Instrument For Hearing

Otoacoustic emissions signal originate from the cochlea.If we measured different frequencies of otoacoustic emissions,we can understand the function of hair cells at different locations within the cochlea.ABR is generated from the auditory nerve.This signal is the EEG signal between the head and the mastoid.By analyzing the ABR signal,we can detect the damage of auditory center function.We extract the otoacoustic emissions signal and ABR signal.and then conduct a comprehensive analysis and processing of the two signals,we can have an overall understanding of the hearing function of the tested.In this paper,we use the combine of nonlinear difference averaging method and time window method to extract the acoustic emission signal.This paper mainly analyzes the weakness of weak signal extraction methods for ABR signal,such as weak amplitude,strong mutation and complex noise interference.Finally,we choose to use the HHT method to extract the noisy ABR signal.The HHT method is an algorithm designed for nonlinear non-stationary signal processing.This method is very suitable for ABR signal processing.But the traditional HHT method has the disadvantage of mode confusion,so we improved the traditional HHT algorithm and we propose a EHHT signal processing method.In order to verify the effect of the EHHT algorithm,a noisy ABR signal model is established in this paper,and the HHT model and EHHT method are used to deal with the model.In order to judge the accuracy of the algorithm,this paper presents a new parameter MSEP.The closer the MSEP value is to 1,the better the effect of denoising is.By analyzing the results of the two algorithms,the EHHT algorithm is proved to be superior to the HHT algorithm and the MSEP value is closer to the ideal data.The results verify the feasibility of the algorithm.After the denoising algorithm is designed,the hardware system is designed in this paper.The whole hardware system is divided into the main control unit,the auditory excitation unit,the ABR signal detection unit and the acoustic emission signal detection unit.In this paper,we make a detailed analysis of each unit.Finally,we designed the upper computer software of the hearing detector,and connected the hardware with the host computer software to carry on the experiment.The feasibility of the whole system is verified by the experimental results of ABR signal,TEOAEs signal and DPOAEs signal.