Occupational hearing loss

Occupational hearing loss is a condition that results from exposure to noise (noise induced hearing loss, NIHL) or to non-noise agents in a work environment. NIHL is usually caused by continuous or intermittent noise exposure which usually develops slowly over several years. Hearing loss from non-noise agents results from exposure to organic solvents, metals, and carbon monoxide. Occupational hearing loss is a prominent global topic affecting individuals, families, businesses and communities, since it is one of the major causes of adult-onset hearing loss at different ages all over the world. Furthermore, occupational noise may have harmful effects eventually independent or associated to hearing loss. Non auditory effects of noise exposure and hearing loss are: physical effects (tinnitus, increased cardiovascular disease risk, fatigue and sleeplessness, increased accident and injury risk, impaired communication), psychological and social effects (annoyance, depression, memory loss, impaired decision making, reduced quality of life, lower confidence and self-esteem, social isolation, relational difficulties) and economic effects (employment and income disruption, increased work absenteeism, increased employee turnover, reduced productivity and performance). Occupational NIHL is typically bilateral, with a classical "notch" at the high frequencies (3000, 4000, or 6000 Hz) and recovery at 8000 Hz, in contrast to presbycusis, indicating a hearing impairment in the middle of the frequency range of human voice. The notch becomes deeper and wider and affects adjacent frequencies in case of continued noise exposure, with a consequent increased impact on speech communications. Making a diagnosis of occupational NIHL is an important step in preventing further hearing loss in the affected worker and identifying the potential for NIHL in co-workers. Complete hearing loss prevention programs are needed to effectively reduce the global burden of occupational hearing loss.