Cochlear maturation and otoacoustic emissions in preterm infants: a time-frequency approach

Click-evoked otoacoustic emissions (CEOAEs) from preterm infants were analyzed to characterize developmental changes of cochlear active mechanisms. Due to their strong time-varying properties, CEOAEs were studied with the wavelet transform. Results obtained in our study give a clear indication that time-frequency characteristics of CEOAEs are not fully developed in preterm babies and reach the complete maturation at about 38 wks post-conception. Also, in agreement with previous physiological and behavioral findings, our results show that the maturation of cochlear active mechanisms is not the same along the cochlear partition but exhibits a spatial gradient proceeding from base to apex.