(PP704) Long Latency Auditory Evoked Potential in Normal Hearing Adults Exposed to Occupational Noise

Our purpose was to compare the electrophysiological findings, through Long Latency Auditory Evoked Potential (LLAEP) of normal hearing individuals exposed and not exposed to occupational noise, seeking to identify parameters that may suggest the presence of hidden hearing loss. Our results showed that, even in the presence of normal hearing thresholds in both groups, the group exposed to occupational noise had lower P3 amplitudes, suggesting that this component may be more sensitive to identify possible changes caused by noise on the central auditory pathways.

 

Summary: 

Background: Recent studies emphasize the importance of evaluating the peripheral and central auditory pathway in workers exposed to occupational noise, since these pathways can suffer damage. This alteration has been called hidden hearing loss, which is characterized by normal hearing thresholds, complaints of speech understanding in the presence of noise and/or in temporal processing. Thus, it is important to assess the Central Auditory Nervous System (CANS), including the cortical portion, through the Long Latency Auditory Evoked Potential (LLAEP) in workers exposed to noise, since previous studies have shown that exposure noise can cause an alteration in cortical processing, even in the presence of normal hearing thresholds, thus affecting the speed, strength and topography of the most central auditory responses. Thus, LLAEP can be of great collaboration for the investigation of CANS in this population, as this may be susceptible to alterations in the auditory pathways resulting from exposure to noise.

Purpose: To compare the electrophysiological findings, through LLAEP, of normal hearing individuals exposed and not exposed to occupational noise.

Methods: The study included 52 male workers, normal hearing, without tinnitus and dizziness, mean age of 36 years, divided into two groups: Study Group (SG), composed of 33 workers exposed to occupational noise, and the Control Group (CG), composed of 19 workers not exposed to occupational noise. The following procedures were performed: otoscopy, immitanciometry, pure tone audiometry, speech audiometry and LLAEP with tone-burst stimulus. For statistical analysis, the ANOVA test was used.

Results: When comparing the two groups, no statistically significant differences were observed for the latencies of components P1, N1, P2, N2 and P3, as well as for the amplitudes P1-N1 and P2-N2, for both ears. For the analysis of the P3 component, it was observed that the CG presented higher amplitude values, with means of 9.12 µV (Right ear - RE) and 8.23 µV (Left ear - LE), compared to the EG, which had means of 6.17 µV (RE) and 5.91 µV (LE), with statistically significant differences for both ears (p-value=0.021 for RE; p-value=0.039 for LE).

Conclusion: Our results showed that, even in the presence of normal hearing thresholds in both groups, the group exposed to occupational noise had lower P3 amplitudes, suggesting that this component may be more sensitive to identify possible changes caused by noise on the central auditory pathways.