Evoked Acoustic Emissions from the Human Ear VI. Findings in Cochlear Hearing Impairment

Click-evoked otoacoustic emissions (CEOAE) were recorded in 28 subjects with mild to moderate flat or steeply sloping cochlear hearing loss. We used the same equipment and recording technique as previously employed in the testing of newborns. A rescaling and subtraction procedure was implemented in an attempt to eliminate the tail of the stimulus artifact. However, in some cases the method also seems to eliminate a true response. In ears with flat losses and with identified CEOAE, no one had a hearing loss exceeding 40 dB HL in the mid-frequency region (0.5, 1 and 2 kHz). Conversely, in ears with flat losses and without CEOAE, no one had a hearing loss less than 30 dB HL in this frequency region. In ears with sloping hearing losses the thresholds at 1 and 2 kHz were most important for the generation of the CEOAE and a significant correlation between the emission amplitude at 70aud (= dB p.e.SPL) and the threshold at 1 kH2 was found.