Modeling of Acoustic Pressure Waves in Level-Dependent Earplugs

Abstract : The report describes both experimental and computational fluid dynamic (CFD) characterizations of acoustic pressure wave travel through a level-dependent hearing protection device, or earplug. The Army's Combat Arms Earplug (CAE) was the device evaluated. Experimental real-ear attenuation at threshold measurements compared very well with design specifications for the CAE. Experimental continuous noise measurements showed higher than desired attenuation in the 1 - to 4-kHz range. Experimental impulse tests provided dynamic response data under field-type conditions and were used to validate the CFD predictions. CFD predictions of the continuous noise input underpredicted the attenuation at higher frequencies. Predicted values of impulse noise attenuation were good, to within 15% of the experimental values.