[Study of denoising in TEOAE signals using an appropriate mother wavelet function]

Matching a mother wavelet to class of signals can be of interest in signal analysis and denoising based on wavelet multiresolution analysis and decomposition. As transient evoked otoacoustic emissions [TEOAES] are contaminated with noise, the aim of this work was to provide a quantitative approach to the problem of matching a mother wavelet to TEOAE signals by using tuning curves and to use it for analysis and denoising TEOAE signals. Approximated mother wavelet for TEOAE signals was calculated using an algorithm for designing wavelet to match a specified signal. In this paper a tuning curve has used as a template for designing a mother wavelet that has maximum matching to the tuning curve. The mother wavelet matching was performed on tuning curves spectrum magnitude and phase independent of one another. The scaling function was calculated from the matched mother wavelet and by using these functions, lowpass and highpass filters were designed for a filter bank and otoacoustic emissions signal analysis and synthesis. After signal analyzing, denoising was performed by time windowing the signal time-frequency component. Aanalysis indicated more signal reconstruction improvement in comparison with coiflets mother wavelet and by using the purposed denoising algorithm it is possible to enhance signal to noise ratio up to dB. The wavelet generated from this algorithm was remarkably similar to the biorthogonal wavelets. Therefore, by matching a biorthogonal wavelet to the tuning curve and using wavelet packet analysis, a high resolution time-frequency analysis for the otoacoustic emission signals is possible

comparison study on the time -frequency specifity of normal cochlear in infants and adults

Analysis of transient evoked otoacoustic emissions [TEOAEs] is of considerable interest due to their close relation with cochlear mechanisms which reveal cochlear function.The particular structure of TEOAEs requires a method with both a satisfactory time and frequency resolution. Among different methods the time -frequency techniques are the most suitable approaches. The aim of this study was to investigate the differences between neonate's cochlear function and adult's cochlear function using time -frequency approaches in TEOAEs. The data of this cohort study was obtained from a sample of 23 normal neonates, aged between 1-28 days, and 31 normal adults, aged between 18 -25 years.TEOAEs with click stimulus were performed for both ears .The TEOAEs files were investigated in time - frequency transform software in off-line mode. The signal to noise ratio [SNR] and response level [dB] of TEOAEs were analysed. The reproducibility, SNR and response level in neonates was greater than adults and in both groups there were no significant difference between responses of males and females and of the right and the left ears. There are differences between neonate's and adult's cochlear response. High frequencies responses are stronger in neonate's cochlea