The Effects of Noise of Military Environments on Auditory System: A Tinnitus and Hypersensitivity to Sound Study

Introduction. Tinnitus and hypersensitivity to sound are abnormal perception of sound, and exposure to noise in military environments is an important etiology of these auditory disorders. In present study, hearing loss, tinnitus and hypersensitivity to sound were evaluated in a group of fighters. Material and Methods. This cross-sectional study was conducted on 250 men who were referred from devotee foundation commission of Tehran with mean age of 41.0 5.3 years. Study was included basic audiology tests (pure-tone, speech, and impedance audiometries) and fill out a questionnaire of hearing disorders (tinnitus and hypersensitivity to sound). Results. The average years of being in military environment was 2.4 1.7 years (range: 1-10 years). Near to two third of subjects had normal hearing, and different degrees of hearing loss with more loss of high frequencies and more frequency of sensory neural hering losses (92.0%) were shown in about one third of patients. Tinnitus was shown in 78.0% of subjects with subjective (98.8%) and continuous (76.0%) charactristics frequently. Tinnitus loudness was in moderate and high levels mostly (84.3%) and no effective treatment has been down generally. Hypersensitivity to sound was revealed in 76.0% of cases with higher annoyance of environmental sounds (78.9 %), and sensitivity to other sensory stimuli specially visual ones (27.6%) too. The burst sound was mentioned as the major cause of hypersensitivity to sound (89.8%) and this disorder was shown in both sudden (57.3%) and gradual (42.7%) forms. Hypersensitivity to sound in 38.%, tinnitus in 35.0%, and hearing loss in 28.0% of cases were mentioned as the main problem. There was significant correlation between hypersensitivity to sound and tinnitus (p<0.001). Conclusion. Exposure to high level of noise is one of the most hazardous factors for the auditoy system and main cause of hearing loss, tinnitus and hypersensitivity to sound. Exposure to noise in military environments can lead to tinnitus and hypersensitivity to sound even without hearing loss, that may result behavioral and social problems.