Otoacoustic emissions in normal-hearing workers exposed to different noise doses.

INTRODUCTION The otoacoustic emission test is useful in monitoring hearing changes not yet detectable in pure-tone audiometry, as well as in monitoring cochlear damage caused by exposure to noise. OBJECTIVE To evaluate distortion product otoacoustic emissions in normal-hearing workers exposed to different occupational noise doses. MATERIALS AND METHOD This is a cohort prospective study performed in metalworking industries, in which normal-hearing workers were assessed by being divided into three different groups: GI not exposed, GII sporadically exposed and GIII often exposed to occupational noise. RESULTS Otoacoustic emission alterations were found in groups II and III bilaterally. Both in the amplitude and in the signal/noise ratio it was observed that as higher was the frequency, worse were the results of GII and GIII (p > 0.001), and the greater the exposure dose is, the lower the averages found in otoacoustic emission. CONCLUSION The otoacoustic emissions are worse in the exposed groups compared to the unexposed group and the greater are the noise dose, worse are the results.