Welcome to CDC stacks |
Stacks Logo
Advanced Search
Select up to three search categories and corresponding keywords using the fields to the right. Refer to the Help section for more detailed instructions.
Clear All Simple Search
Advanced Search
Hearing Protector Attenuation and Noise Exposure Among Metal Manufacturing Workers
  • Published Date:
    2019 May/Jun
  • Source:
    Ear Hear. 40(3):680-689
  • Language:

Public Access Version Available on: May 01, 2020, 12:00 AM information icon
Please check back on the date listed above.
  • Alternative Title:
    Ear Hear
  • Description:

    This study utilized personal noise measurements and fit-testing in order to evaluate the association between noise exposures and personal attenuation rating (PAR) values among participating workers, and second, to compare the attenuated exposure levels received by the workers and the British Standards Institute’s (BSI) recommended noise exposure range of 70–80 dBA.


    We measured HPD attenuation among a sample of 91 workers at 2 US metal manufacturing facilities, through performance of personal noise dosimetry measurements and HPD fit-testing over multiple work shifts. We compared this testing with participant questionnaires and annual audiometric hearing threshold results.


    The average 8-hr Time-weighted Average (TWA) noise exposures for study participants was 79.8 dBA (SD 7.0 dBA), and the average PAR from fit-testing was 20.1 dB (± 6.7 dB). While differences existed between sites, 84% of the 251 PAR measurements resulted in effective protection levels below the recommended 70 dBA (indicating overprotection), while workers were underprotected (i.e., effective exposures >80 dBA) during <1% of monitored shifts. Our results also demonstrated a significant positive relationship between measured noise exposure and PAR among non-custom-molded plug users (p=0.04). Non-custom-molded plug wearers also showed a significant increase in PAR by sequential fit-test interaction (p=0.01), where on average, subsequent fit-testing resulted in increasingly higher HPD attenuation. Workers at site 1 showed higher PARs. PARs were significantly related to race, even when adjusting for site location. While age, hearing threshold level, task, and self-reported tinnitus showed no significant effect on individual PAR in an unadjusted model, site, race, and sand- or water-blasting activities were significant predictors in adjusted models. Within-worker variability in TWAs and PARs across repeated measurements was substantially lower than variability between workers.


    Careful selection of HPDs is necessary to minimize instances of over-protection to workers in low and moderate occupational noise environments. The use of fit-testing in hearing conservation programs to evaluate PAR is recommended to avoid overprotection from noise exposure while also minimizing instances of under-attenuation.

  • Subject:
  • Pubmed ID:
  • Pubmed Central ID:
  • Document Type:
  • Collection(s):
  • Main Document Checksum:
  • Supporting Files:
    No Additional Files
No Related Documents.
You May Also Like: