Auditory monitoring by means of evaluation of the cochlea in soldiers of the Brazilian Army exposed to impulse noise.

INTRODUCTION Exposure to continuous or impulse noise may lead to High Sound Pressure Induced Hearing Loss (HSPIHL) or to acoustic trauma in soldiers. Auditory evaluation by means of evoked otoacoustic emissions (EOAE) has been demonstrating its importance in the detection of subtle changes in cochlear function still unidentified in threshold tone audiometry in subjects exposed to noise. OBJECTIVE Studying Distortion product otoacoustic emissions (DPOAEs) before and after exposure to impulse noise in soldiers of the Brazilian Army. MATERIAL AND METHOD This is an analytical, observational, longitudinal and prospective study. Auditory evaluation was performed by means of DPOAEs in 60 soldiers before and after exposure to impulse noise, of whom 30 were reevaluated immediately after exposure and 30 were reevaluated 24 hours after exposure. RESULTS The statistical analysis revealed that both groups reevaluated after exposure to impulse noise showed a decrease in amplitudes in comparison with the tests before exposure. As for the signal/noise ratio, there was a significant difference at the frequencies of 6 and 8KHz and there was a significant association between a tinnitus complaint and the group reevaluated immediately after exposure to noise. CONCLUSION The DPOAE test proved sensitive to detect subtle shifts after exposure to impulse noise, both with regard to the amplitude criterion and with regard to the signal/noise ratio even 24 hours after exposure. This demonstrated the applicability of the DPOAE test in monitoring the hearing of soldiers exposed to impulse noise.