Role of distortion product otoacoustic emissions in the early identification of occupational noisedinduced hearing loss

OBJECTIVE To analyse the pure tone threshold(PTA)and distortion product otoacoustic emissions(DPOAE)features in occupational noiseinduced hearing loss,and investigate the role of DPOAE in the early identification of occupational noise-induced hearing loss(NIHL).METHODS PTA and DPOAE were performed both in 15(30 ears,control group) health young adults and 36(69 ears,experimental group)workers from the power plant who have been working in loud sounds environment.According to the result of PTA,the experimental group was divided into the normal hearing group and the hearing loss group.The PTA thresholds and amplitudes of DPOAE were compared and analyzed.RESULTS 1.The PTA of hearing loss group at 2-8 kHz are extremely increased(P0.05 or P0.001);2.Both the DPOAE amplitudes of the total experimental group and the hearing loss group at 1.5-8 kHz were lower than that of the normal controls(P0.05 or P0.001);3.The DPOAE amplitudes of normal hearing group at 4-8 KHz were drcreased too(P0.05).CONCLUSION The DPOAE has an important role in early diagnosis and detection of occupation NIHL,and the 4-8 kHz may be the earliest frenquency area to be damaged.