The impact of noise in occupational settings on hearing has been recognized since the Middle Ages. According to statistics from the International Noise Control Association (A.I.C.B), in developed industrial countries, about 1/4 to 1/3 of workers are exposed to noisy environments.
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Occupational deafness, which was once at the bottom of the list of occupational diseases, has now risen to the top and is on the rise.
Occupational deafness is a type of permanent damage that never recovers, even after exposure to noise has ceased, due to changes in the inner ear caused by noise, particularly affecting the organ of Corti and resulting in damage to hair cells. Therefore, preventing occupational deafness for workers is crucial, and individuals working in noisy environments must understand how to protect themselves.
Noise is described as unwanted sounds that can have harmful effects on health and human life. Noise-induced hearing loss typically stems from high-frequency sounds with significant intensity, combined with vibrations and prolonged working hours, specifically: noise levels above 90 dB for 6-8 hours a day over a period of 3-6 months. This condition is commonly found among workers in shipyards, textile factories, and military tank or armored units.
Occupational deafness progresses slowly and worsens over time, with the primary symptom being bilateral hearing loss that is generally equal. Early signs are often observed in patients working in noisy environments, where fatigue, ear pressure, tinnitus, and diminished hearing clarity at the end of shifts may occur after several weeks or months. These symptoms completely resolve with rest.
This latent stage can last for several years, as initial hearing loss is typically only at high frequencies while conversational frequencies remain normal, meaning it does not yet impact daily activities, and patients may not pay attention to it. In later stages, those with occupational deafness become aware of their condition when they experience significant hearing loss and difficulty communicating, often accompanied by tinnitus.
Prevention
Various technical measures are employed, such as reducing noise at the source or isolating the noise-generating sources through the design and arrangement of machinery. Workers should use noise protection devices such as earplugs, earmuffs, or helmets with ear protection. Medical measures include regular hearing assessments every 6 months to 1 year for those working in noisy environments. Scheduling work hours for employees in noisy areas should be staggered and rotated to avoid prolonged exposure to noise.
