Risk factors of hearing loss among Thai naval divers

Abstract

Copyright © (2018) by International Institute of Acoustics & Vibration. All rights reserved. There are many causes of hearing loss, including noise, drugs, trauma, stroke, Meniere's disease and barotrauma. Among divers, dive-related permanent hearing loss resulting from ear barotrauma or decompression sickness is possible. This study aimed to clarify the prevalence of hearing loss and its risk factors among Thai naval divers. The subjects were 263 military divers in the Royal Thai Navy, aged at 22 to 55 years. All subjects were asked to fill in a questionnaire on characteristics, personal histories, working conditions and protective behaviors. Audiometrie threshold testing was performed at the audiometric frequencies of 0.5, 1, 2, 4 and 8 kHz in a sound proofroom. The results are as follows. Ninety-seven percent of the subjects had the experience of diving. The average working year was 16.1 years. The subjects dived 2.1 times a week until to 132.3 fsw (4-5 ata) in average. Sixty-one percent of them had hearing loss. The hearing losses were classified into 4 kHz-dip (12.5%), high frequency hearing loss (16.7%) and mixed hearing loss (31.9%). In order to determine the diving exposure dose for the subjects, total diving depth (TDD) was used as the index. The TDD was calculated from working years, diving times a week and diving depth. Partial correlation coefficient adjusted age showed that working years, diving times a week, and diving depth were not related to hearing levels except relationship between diving times a week and hearing level at 0.5 kHz. The TDD was significantly related to hearing levels at 0.5, 1 and 4 kHz. Multiple linear regression analysis showed the hearing level associated with TDD and some protective behaviors. These results suggest that the Royal Thai Navy should manage diving conditions for conserving hearing acuity of naval divers.