Hearing damage in military service. A study on 38,294 conscripts.

Area of Science:

• Audiology
• Occupational Health
• Military Medicine

Background:

• Noise-induced hearing loss is a significant occupational hazard.
• High-frequency hearing defects are common in young adults.
• Military basic training involves prolonged exposure to noise.

Purpose of the Study:

• To investigate the incidence and characteristics of noise-induced high-frequency hearing deterioration in conscripts during basic training.
• To assess the impact of pre-existing hearing status on the risk of developing noise-induced hearing deterioration.
• To evaluate the implications of hearing data for conscript assignment to noisy environments.

Main Methods:

• Audiometric assessment of 38,294 conscripts before and after basic training (mean 245 days).
• Analysis of high-frequency hearing deterioration, its laterality, and symptomatic levels.
• Correlation analysis between initial hearing status and subsequent hearing changes.

Main Results:

• 29% of conscripts had pre-existing high-frequency hearing defects.
• 5% developed high-frequency hearing deterioration post-training, often unilateral or asymmetrical.
• 0.5% experienced symptomatic hearing loss, with 0.03% meeting criteria for 10% hearing disability.
• Conscripts with pre-existing hearing loss had a significantly higher incidence (17%) of deterioration compared to those with normal hearing (3%).

Conclusions:

• Military basic training can lead to significant high-frequency hearing deterioration.
• Pre-existing sensorineural hearing loss is a risk factor for noise-induced hearing deterioration.
• Pre-enlistment audiometric screening is crucial for assigning conscripts to appropriate training and posts to mitigate hearing damage.