The use of cortical evoked response audiometry in the assessment of noise-induced hearing loss.

Abstract

The study aims were to determine the incidence of exaggerated hearing thresholds in individuals complaining of noise-induced hearing loss (NIHL) as a result of impulse noise using cortical evoked response audiometry (CERA) and to identify any associated audiometric features. We conducted an office-based study. In this prospective case series, 1154 males complaining of NIHL were assessed with pure tone audiometry; 673 had CERA. Pure tone averages (PTA) and hearing disability were calculated using the Irish and American Medical Association systems. A PTA of >10 dB worse than the CERA average was considered evidence of exaggerated thresholds. The mean PTA was 33 dB. Seventy-two percent had a hearing disability of an average of 26% when assessed by the Irish system. Fifty-four percent had a hearing disability of an average of 30% when assessed by the American Medical Association system. Twenty-six percent of subjects had exaggerated thresholds based on CERA. A binaural hearing threshold of >25 dB at 500 Hz had a sensitivity of 94% and a specificity of 59% for the detection of exaggerated thresholds. Exaggerated hearing thresholds are common. A hearing threshold of >25 dB at 500 Hz should be considered an indication for CERA testing.