Law Enforcement Head-Borne Personal Protective Equipment Hearing Attenuation

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA498436&Location=U2&doc=GetTRDoc.pdf

Law Enforcement Head-Borne Personal Protective Equipment Hearing Attenuation
Li, Qi; Haijeck, Joshua; and Burchfield, Tom

ECBC-CR-103
April 2009

Test methods were developed to quantify and assess the effects of personal protection equipment (PPE) on hearing. The tests use a head and torso simulator that is able to don PPE and employs advanced acoustic, signal processing, and measurement techniques. The tests measure localization and speech intelligibility effects of PPE. The methods also assess the effects of noise generated by PPE fabric and/or electro/mechanical noise. Localization effects are evaluated in terms of the Head-Related Transfer Function (HRTF). Speech intelligibility is
evaluated using the Speech Transmission Index (STI). Results show that HRTF and STI scores are significantly altered with various PPE and PPE-created noise.