Use of ABR threshold and OAEs in detection of noise induced hearing loss.
OBJECTIVE
To determine which measure is the most sensitive to noise induced hearing loss (NIHL): auditory nerve brainstem response (ABR), distortion product otoacoustic emission (DPOAE) or transient evoked otoacoustic emission (TEOAE), and how to assess possible changes in these responses.


METHODS
Four groups of rats were exposed to various durations of 113 dB SPL broadband noise: 5 or 10 minutes (temporary changes in cochlear function), and 3 or 4 hours (permanent changes). Group means and data from individual animals were compared before and after exposure.


RESULTS
Mean group DPOAE amplitude reduction showed no clear advantage over mean ABR threshold elevation in detection of temporary and permanent NIHL. Data from individual rats, however, indicated a clinical advantage for DPOAEs in detecting slight temporary, but not permanent, changes. TEOAEs were more sensitive in detecting changes in individual rats than as a group measure.


CONCLUSIONS
TEOAE and DPOAE monitoring may improve detection of NIHL, though it should be used in conjunction with audiometric threshold monitoring.
Fraenkel
Rachel
R
Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Freeman
Sharon
S
Sohmer
Haim
H
D000161:Acoustic Stimulation; D000818:Animals; D003051:Cochlea / Q000293:injuries / Q000503:physiopathology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D051381:Rats