title: Hearing.
abstract: The main hazard for hearing in the workplace is noise. Organic solvents and heavy metals may increase the danger of developing occupational hearing loss, particularly in the case of co-exposure with noise. While noise produces damage predominantly to the cochlea, chemicals may be responsible for pathologic changes in both peripheral and central parts of the auditory pathway. Noise-induced hearing loss develops slowly over the years, although its progression is most dynamic during the first 10-15 years of exposure. Pure-tone audiometry indicates a bilateral sensorineural hearing loss, affecting predominantly high frequencies, with typical notch at 3-6 kHz in the early stages of the disease. Where there is co-exposure to noise and chemicals, the noise effect on hearing threshold shifts is dominant; however chemicals seem to increase the vulnerability of the cochlea to the damage by noise, particularly at its low and moderate levels. According to European Directive 2003/10/EC, the employer is obliged to implement hearing prevention programs when the A-weighted equivalent 8-hour level of noise (LAEX8 hr) exceeds 80 dB. Since chemicals may impair intelligibility of speech despite a lack of audiometric hearing threshold shift, implementation of speech audiometry, particularly speech in noise tests, is recommended in prevention programs.
authors.affiliation: Department of Audiology and Phoniatrics, Nofer Institute of Occupational Medicine, Lodz, Poland. Electronic address: marsliw@imp.lodz.pl.
authors.forename: Mariola
authors.initials: M
authors.lastname: Sliwinska-Kowalska
mesh_terms: D006311:Hearing Disorders / Q000209:etiology*; D006801:Humans; D009622:Noise / Q000009:adverse effects*; D016273:Occupational Exposure
keywords: asphyxiants; hearing loss; heavy metals; noise; organic solvents; prevention