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Review
. 2023 Jun 16;44(4):485-502.
doi: 10.1055/s-0043-1769498. eCollection 2023 Nov.

Noise Exposure and Hearing Loss among Workers at a Hammer Forge Company

Scott E Brueck  1 , Judith Eisenberg  1 , Edward L Zechmann  1 , William J Murphy  2 , Edward Krieg  1 , Thais C Morata  1
Affiliations
Review

Noise Exposure and Hearing Loss among Workers at a Hammer Forge Company

Scott E Brueck et al. Semin Hear. .

Abstract

The National Institute for Occupational Safety and Health (NIOSH) evaluated continuous and impact noise exposures and hearing loss among workers at a hammer forge company. Full-shift personal noise exposure measurements were collected on forge workers across 15 different job titles; impact noise characteristics and one-third octave band noise levels were assessed at the forge hammers; and 4,750 historic audiometric test records for 483 workers were evaluated for hearing loss trends. Nearly all workers' noise exposures exceeded regulatory and/or recommended exposure limits. Workers working in jobs at or near the hammers had full-shift time-weighted average noise exposures above 100 decibels, A-weighted. Impact noise at the hammers reached up to 148 decibels. Analysis of audiometric test records showed that 82% of workers had experienced a significant threshold shift, as defined by NIOSH, and 63% had experienced a standard threshold shift, as defined by the Occupational Safety and Health Administration (OSHA). All workers with an OSHA standard threshold shift had a preceding NIOSH significant threshold shift which occurred, on average, about 7 years prior. This evaluation highlights forge workers' exposures to high levels of noise, including impact noise, and how their hearing worsened with age and length of employment.

Keywords: hammer forge; hearing loss; impact noise; noise; noise-induced hearing loss.

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Conflict of interest statement

Conflict of Interest None declared.

Figures

Figure 1
Figure 1
Hammer operator at a pneumatic forge hammer. (Photo by NIOSH.)
Figure 2
Figure 2
Noise exposure time-history profile for a hammer operator, trim press operator, and heater.
Figure 3
Figure 3
Shear operator's noise exposure time-history profile.
Figure 4
Figure 4
Sequence of hammer strikes during forging of an ingot at a 5,000-pound hammer (left) and the sound pressure waveform for a single hammer strike during the sequence (right). The peak impact sound pressure of 300 Pa is equivalent to a SPL 143.5 dB.
Figure 5
Figure 5
Stacked bar charts showing the relative proportion of impact peaks within three different SPL ranges during hammer strikes.
Figure 6
Figure 6
One-third octave band measurement results at a 5,000-pound hammer (left) and 10,000-pound hammer (right).
Figure 7
Figure 7
Forgings being dumped from a shot blast onto a vibrating conveyor pan and moving down the conveyor to fall into a metal bin. (Photo by NIOSH.)
Figure 8
Figure 8
Elapsed time from NIOSH-defined significant threshold shift to OSHA-defined standard threshold shift.
Figure 9
Figure 9
Comparison of hearing threshold levels after 10 years of noise exposure in forge workers by hire date (before or after 1980).
Figure 10
Figure 10
Comparison of forge worker hearing threshold levels (HTLs) to the ISO 1999:2013 standard, Annex B3 reference (unscreened) population HTLs.
See this image and copyright information in PMC

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