| Otoacoustic emissions (OAEs) is are lease of audio-frequency energy from the outer hair cells of the inner ear into the external ear canal, transmitted though the ossicular cnain and tympanum. It was first reported in 1978 by Kemp by placing a earphone-micphone probe in the ear canal. OAEs provides direct evidence for the cochlea active process mechanism and a new idea to research the auditory mechanism .At the same time, as an objective means to assess the cochlear functional status, otoacoustic emissions has been studied largely to find out the relation between otoacoustic emissions and various hearing impairments, and further establish a new diagnostic tool.Transiently evoked otoacoustic emissions (TEOAEs) tests the transient response of the cochlea, it stabilizes over along term, can be detected in 100% normal ears, and more sensitive to injuries, Also it is an objective, noninvasive and quick method. TEOAEs has been widely researched and used.So far, there are a few OAEs systems in our country, all the OAEs systems are expensive, and not convenient for spread. In addition, their hardware systems are too complex to maintain and repair. Hence, this dissertation designs an embedded smart hearing system ,which use simply and is reliable and cheap, in order to fulfill the need of middle and small cities, especially the country.This dissertation design a OAEs hardware system and software system, and focuses on OAEs hearing detection algorithm for the study: Firstly it design a algorithm for the sensor detection; Then it uses a variety of noise elimination and pseudo-track removal algorithms in comprehensive ,and gets a good results; Finally 3dB determine methods and factors related determine methods were used to detect OAEs signals; and Analysis the test results in detail. This dissertation also introduces the uClinux operating system transplant to ADSP-BF531 platform. |
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