Design Of Otoacoustic Emission Detection System

Otoacoustic Emission(OAE)is an audio energy generated in the cochlea and released to the external auditory canal via ossicular chain and tympanum.The discovery of otoacoustic emission reflects that the cochlea not only can recognize the external sound,but also has the function of actively generating audio energy.At present,as a non-invasive,efficient,accurate and objective hearing detection method,otoacoustic emission(OAE)has been widely used in clinical practice,and is the main detection method for newborn hearing screening.At the same time,otoacoustic emission(OAE)detection of mice is an important method to screen some ototoxic drugs,which is also of great significance to the clinical study of hearing.Otoacoustic emissions are divided into several categories.At present,the most widely used clinical products are distortion product otoacoustic emissions(DPOAE)and transient evoked otoacoustic emissions(TEOAE).This paper mainly describes the design of the distortion product otoacoustic emission detection system,and carried out some related experiments.The subjects in the article are human and mouse.Because of the large difference in the hearing range between human and mouse,different DPOAE detection systems were designed for different experimental subjects.The main work consists of the following sections.The first is the choice of speakers and microphones.For the human ear,the measurement frequency range is 1-6 KHz,the frequency is relatively low,and most of the speakers can meet the measurement requirements.However,the maximum frequency of mouse DPOAE detection is 32 KHz,and the frequency is relatively high,so it is necessary to select a specific high frequency horn to better complete the measurement.A microphone is a key device for converting an acoustic signal into an electrical signal.Only when the sound signal is converted into an electrical signal can the next signal be processed,so it is very important to select a suitable microphone.In this paper,a probe is designed to integrate the microphone and the speaker to meet the measurement needs.The second is to design the signal processing circuit.Since the OAE signal is a very weak sound signal,it is easy to be submerged in environmental noise,and it is necessary to design a suitable amplification filter circuit.In this paper,the MAX9812 and AD8529 are used to design a suitable signal processing circuit,which is tested and tested to meet the measurement requirements.Then choose the appropriate signal processing method.In this paper,the coherent averaging method is used to measure the signal-to-noise ratio of the title signal,and then the FFT is used for spectrum analysis to obtain the DPOAE signal.Finally choose the appropriate data acquisition card.For the DPOAE of people with lower measurement frequency,the multimedia sound card can complete the acquisition of OAE signal data;however,the detection frequency of mouse DPOAE is up to 32 KHz,and the multimedia sound card can not meet the sampling requirements,so choose NI USB.As a data acquisition device,the-6356 device can perform data acquisition very well.