Comparison of distortion product otoacoustic emissions and pure tone audiometry in occupational screening for auditory deficit due to noise exposure

Objective: To examine whether distortion product otoacoustic emissions can serve as a replacement for pure tone audiometry in longitudinal screening for occupational noise exposure related auditory deficit. Methods: A retrospective review was conducted of pure tone audiometry and distortion product otoacoustic emission data obtained sequentially during mandatory screening of brickyard workers (n = 16). Individual pure tone audiometry thresholds were compared with distortion product otoacoustic emission amplitudes, and a correlation of these measurements was conducted. Results: Pure tone audiometry threshold elevation was identified in 13 out of 16 workers. When distortion product otoacoustic emission amplitudes were compared with pure tone audiometry thresholds at matched frequencies, no evidence of a robust relationship was apparent. Seven out of 16 workers had substantial distortion product otoacoustic emissions with elevated pure tone audiometry thresholds. Conclusion: No clinically relevant predictive relationship between distortion product otoacoustic emission amplitude and pure tone audiometry threshold was apparent. These results do not support the replacement of pure tone audiometry with distortion product otoacoustic emissions in screening. Distortion product otoacoustic emissions at frequencies associated with elevated pure tone audiometry thresholds are evidence of intact outer hair cell function, suggesting that sites distinct from these contribute to auditory deficit following ototrauma.