Background: Distortion product otoacoustic emissions (DPOAEs) are a promising screening technique for the early detection of subtle noise induced cochlear function changes.
Objectives: To determine the applicability of DPOAEs as a health surveillance technique for the early detection of noise induced hearing loss (NIHL) in workers at a steel manufacturing industry.
Methods: DPOAEs were recorded in 20 participants with no history of occupational noise exposure and 20 participants exposed to noise in the steel manufacturing industry. Participants were not exposed to noise for at least 48 hours prior to testing. All participants were male with normal audiometric thresholds of ?15 dB HL. The DPOAE presence and response amplitude levels for different frequencies were compared between the two groups. The study further evaluated the short-term test-retest repeatability of DPOAE measurements, and also compared the total test duration of performing DPOAEs to the duration of screening audiometry.
Results: The noise exposed group had statistically significantly lower DPOAE response amplitudes than the control group for all the tested frequencies; (pɘ.001) at 2002 to 4004 Hz, and (p=0.01, p=0.001) at 6348 and 7996 Hz respectively, suggesting more cochlear damage in the noise exposed group due to early outer hair cell damage. DPOAEs showed very good reproducibility, and the average duration of performing a set of DPOAEs was significantly shorter (461 ± 68.2 seconds) than the duration of performing audiometry (591 ± 76.9 seconds), pɘ.001.
Conclusion: DPOAEs appeared to be a sensitive technique in detecting noise induced subtle cochlear function changes. DPOAEs could be used as a health surveillance technique for the early detection of NIHL in the steel manufacturing industry.
Dissertation (M Communication Pathology)--University of Pretoria, 2017.