In-Depth Survey Report: Comparison of the Performances of Three Acoustic Test Fixtures Using Impulse Peak Insertion Loss Measurements; Rudyard, Michigan

Details

• Personal Author:
  Fackler, Cameron J. ; Finan, Donald S. ; Flamme, Gregory A. ; Khan, Amir ; Lankford, James E. ; Meinke, Deanna K. ; Murphy, William J. ; Shaw, Peter B. ; Stewart, Michael
• Corporate Authors:
  National Institute for Occupational Safety and Health. Division of Applied Research and Technology
• Description:
  The purpose of this study was to evaluate three acoustic test fixtures (ATFs) using four hearing protector conditions and the methods in the ANSI/ASA S12.42-2010 standard. In 2009, the U.S. Environmental Protection Agency (EPA) proposed an impulse noise reduction rating (NRR) for characterizing the performances of hearing protection devices using the impulse peak insertion loss (IPIL) methods as outlined in the ANSI/ASA S12.42-2010 standard. The proposed EPA method measures the occluded and unoccluded response of an ATF in the presence of impulse noise at levels of 132, 150 and 168 decibels peak sound pressure level (dB peak SPL). The IPIL is the mean difference between the unoccluded and occluded responses measured in the fixture. The performances of the high-fidelity (HiFi) Etymotic Research ETYPlugs earplug, the electronic level-limiting Etymotic EB-1 BlastPLG(TM) earplug, the 3M(TM) Peltor(TM) TacticalPro Communications Headset earmuff and the dual protector combination of the ETYPlugs earplug and the TacticalPro earmuff were evaluated on a single-ear and two dual-ear ATFs at the three impulse levels listed above. The French German Research Institute de Saint Louis (ISL) built both an unheated single-ear ATF (ISL-1) with 10 millimeter (mm) ear canals and a dual-ear heated ATF (ISL-2) with 12 mm ear canals. G.R.A.S. Sound & Vibration (GRAS) provided a heated dual-ear fixture (GRAS-45CB) with 18 mm ear canals. Five samples of each protector were fitted five times on each fixture or inserted in the ear canals of each fixture. For each fitting, three shots were measured. Impulses were generated using a Colt AR-15 0.223 caliber rifle. ETYPlugs earplug exhibited an increase in IPIL on each fixture as the impulse levels increased. Overall, for this earplug the ISL-2 fixture exhibited greater IPIL values compared to the dual-ear GRAS 45CB fixture while the ISL-1 fixture had the lowest IPIL values across all three impulse levels. EB-1 BlastPLG(TM) earplug tested in the unity gain mode also displayed an increase in IPIL with increasing impulse levels for all three fixtures. The GRAS 45CB fixture displayed the highest IPIL values for this protector compared to the ISL-1 and ISL-2 fixtures. The two ISL fixtures exhibited similar IPIL results at the 132 and 150-dB impulse levels but at the 168-dB impulse level the ISL-2 fixture was approximately 7.0 dB greater. TacticalPro(TM) earmuff also provided an increase in IPIL on all three fixtures with increasing impulse levels. For this earmuff, both of the ISL fixtures exhibited greater IPIL values compared to the GRAS 45CB fixture. The ISL-1 and ISL-2 fixtures had comparable IPIL at all three impulse levels. For the dual protection condition, the IPIL also increased with increasing impulse levels. Overall, the single-ear and dual-ear ISL fixtures exhibited significantly greater IPIL compared to the GRAS 45CB fixture across all three impulse levels. The average IPIL differences observed between the ISL-1 fixture and the GRAS fixture were approximately 14.8 dB while the average IPIL difference observed between the ISL-2 fixture and the GRAS 45CB fixture were approximately 16.2 dB across all three impulse levels. The mean IPILs increased with increasing impulse peak pressure on all three ATFs for all four hearing protection devices tested in this study. This research has demonstrated that the three fixtures evaluated using the ANSI/ASA S12.42-2010 method and four hearing protection conditions did not generate similar IPIL values and the differences varied as a function of hearing protector type and impulse level. In general for the two dual-ear fixtures, the earplug-only conditions generated comparable IPIL while for the single-ear fixture the earplug-only conditions produced lower IPILs. The earmuff only and the dual-protection conditions produced similar IPIL for the ISL-1 and ISL-2 fixtures but consistently generated lower IPIL for the dual-ear GRAS fixture. It is recommended the differences observed in the performances of the GRAS and ISL-2 fixtures with the earmuff and dual-protection conditions should be further investigated with the newer and improved version of the GRAS fixture. Furthermore, the ear canal of the ISL-2 fixture should be longer than 12 mm to permit testing earplugs that require more insertion depth such as formable plugs.
• Subjects:
  Ear Engineering Hearing Loss, Noise-Induced Laboratories Noise Noise, Occupational Occupational Health Personal Protective Equipment Protective Clothing Safety Sense Organs

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• Keywords:
  Acoustics American National Standards Institute Analytical-methods Control-technology Ear-protection Ear-protectors Engineering-controls Equipment-design Equipment-reliability Gunshot Noise Hearing-protection Impulse-noise Impulse Noise Laboratory-testing Measurement-equipment Noise-levels Noise-measurement Noise-protection Noise Induced Hearing Loss OSHA Region 5 Performance-capability Personal-protective-equipment Sound Standards Testing-equipment

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• Series:
  Engineering and Physical Hazards Survey Reports
• DOI:
  https://doi.org/10.26616/NIOSHEPHB35014a
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Genre:
  Field Study
• Place as Subject:
  Michigan ; Rudyard (MI) ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology ; EPHB - Engineering and Physical Hazards Branch
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-40
• NIOSHTIC Number:
  nn:20046213
• NTIS Accession Number:
  PB2015-104154
• Citation:
  Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 350-14a, 2015 Feb ; :1-40
• Federal Fiscal Year:
  2015
• NORA Priority Area:
  Construction ; Manufacturing
• Peer Reviewed:
  False
• NAICS and SIC Codes:
  928110 - National Security - (NAICS)
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:100784f2d018d6aa979f9a790501f87f629fc748819d8af305b96b2f0608e258084444a4de25588e07d21b473bd4f1f9040a7617fa83606f61d2173b850ca053
• Download URL:
  https://stacks.cdc.gov/view/cdc/174997/cdc_174997_DS1.pdf
• File Type:
  [PDF - 1.43 MB ]