Accession Number:

ADA622427

Title:

Level-Dependent Nonlinear Hearing Protector Model in the Auditory Hazard Assessment Algorithm for Humans

Descriptive Note:

Final rept. 1 Oct 2013-31 Oct 2014

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD HUMAN RESEARCH AND ENGINEERING DIRECTORATE

Personal Author(s):

Report Date:

2015-04-01

Pagination or Media Count:

66.0

Abstract:

US Army Research Laboratory technical report ARL-TR-6748, Using the Auditory Hazard Assessment Algorithm for Humans AHAAH With Hearing Protection Software, Release MIL-STD-1474E, includes AHAAH with a Hearing Protector Module HPM modeling all hearing protector devices HPDs as level-independent linear devices. Listed HPDs include several level-dependent nonlinear LDNL earplugs. These are modeled linearly, based on Real Ear Attenuation at Threshold REAT measurements in closed and open modes. When analyzing auditory hazards with LDNL HPDs applied as linear devices based on REAT measurements, results are generally overly protective, since REAT measurements do not reflect increased attenuations for higher waveform pressures. Several MIL-STD-1474E Working Group members felt LDNL HPD performance must be accurately described and incorporated into AHAAH cited in the MIL-STD. Consequently, a nonlinear pressure-amplitude-dependent model for performance of LDNL HPDs was created and added to the HPM of version 2.1 of AHAAH Release MIL-STD-1474E. We describe LDNL modifications to AHAAH s HPM and validate the LDNL HPD model by comparing predicted and measured insertion losses ILs and waveforms under the HPD, for increasingly intense waveforms. A LDNL HPM will more accurately predict ILs and waveforms under HPDs and support more accurate auditory hazard assessments for complex impulsive waveforms encountered in real situations.

Subject Categories:

  • Anatomy and Physiology
  • Numerical Mathematics
  • Computer Programming and Software
  • Radiofrequency Wave Propagation
  • Protective Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE