Effects of Exposure to Impact Noise on the Hearing of Armed Forces and Evaluation of the Methods to Control and Decrease its Consequences: A Review Study

Background and Aim: Exposure to impact noise (short-term, high intensity) higher than permitted levels results in injury to the auditory system. Armed forces are one of the occupational groups exposed to these types of noises resulting from gunshots. In this study, relevant articles and research on the adverse effects of impact noise, hearing loss, and tinnitus in armed forces and effective control methods are reviewed. Methods: In this review study, the databases of Web of Science, Scopus, PubMed, Science Information Database (SID), Islamic World Science Citation Center (ISC), and Science Direct were searched with the keywords including noise-induced hearing loss, armed forces, impact noise, control and exposure in armed forces and shooting range. Through determining entrance and exit indicators and consultations among writers, from 68 evaluated articles, 42 entered the study, and 26 were removed. Results: Several studies measured the gunshot noise level and found that exposure to this noise resulted in different auditory complications depending on the frequency and intensity of exposure. Baseline characteristics and lifestyle are parameters involved in developing noise-induced hearing loss. Active and passive noise control methods and the use of hearing protection devices are among the measures adopted to reduce the intensity of exposure and decrease the detrimental effects of noise on the auditory system. Conclusion: The use of hearing protection with an active noise cancellation has been developing during the past years, however, it is recommended to use both noise control engineering and hearing protection to reduce the highest level of harmful noise possible when firing a weapon. It should be noted that to prevent hearing loss in the military staff, it is necessary to build medical records upon recruitment for hearing monitoring and conduct periodic examinations.