Noise levels and hearing thresholds in the drop forging industry.
Taylor-W; Lempert-B; Pelmear-P; Hemstock-I; Kershaw-J
J Acoust Soc Am 1984 Sep; 76(3):807-819
The relationship between noise level and hearing loss was determined in drop forging facilities. Noise data was obtained from the forge and press shops of seven forges in the United Kingdom between 1970 and 1972. Data collection involved both tape recording and personal dosimetry performed simultaneously. Audiometric testing of 10,261 workers within the facilities were assessed with regard to occupation, clinical observations, and personal history questionnaires. The comparison population included 340 men and women who worked in the offices and canteens of the forges, had not been exposed to noise levels greater than 85 decibels, and were free from any ear pathology. The mathematical formulae for determining the noise related hearing loss from exposure to continuous noise were described. The percentile hearing level distributions as a function of test frequency for press and hammer operators were greater than the comparison population, and the difference increased with age from 20 through 50 years. Comparisons between the press and hammer operators showed more hearing loss for the hammer operators at the test frequencies of 500 to 3000 hertz after age 35. Equivalent continuous noise levels for press and hammer operators were 99 and 108 decibels-A, respectively. The hearing levels of press and hammer operators were similar for mean exposure times of less than 10 years. The authors conclude that hearing loss due to impact noise is greater than or equal to hearing loss attributable to continuous noise for exposures longer than 10 years.
NIOSH-Author; Metalworking-industry; Industrial-equipment; Noise-exposure; Noise-induced-hearing-loss; Industrial-hygiene; Audiometry; Impact-noise; Occupational-hazards; Worker-health
Journal of the Acoustical Society of America