A Finite Element-Based Acoustic Engineering Design Program for Advancements in Passive Noise Reduction Performance of Helmet Mounted Noise Defenders

"Adequate hearing protection for U.S. Navy crew personnel is mandatory and may be achieved through the use of earcups, earplugs, or both. Donning only the earcups or only the earplugs is referred to as single hearing protection (SHP), while the use ofearplugs under earcups is called double hearing protection (DHP). This Phase I program offers a comprehensive engineering study and design strategy that relies on Acoustic Finite Element Analyses (AFEA) and correlated test-based models to prioritize allspecific acoustic phenomena that affect SHP noise transmission to the ear across the entire audible frequency bandwidth. This prioritization of controlling noise mechanisms will then form a much-needed framework for exploitation of new design principlesin both SHP and DHP applications. The Phase I Option and Phase II will continue the evolution of the model to address further problems in the DHP application. Finally, comparisons between the DHP FEA results to measured DHP system performancemeasurements, will help to identify the absolute best possible noise attenuation that can be achieved in the occluded space, not accounting for bone conduction paths. The most significant benefit of the Phase I program will be the contribution of adetailed acoustic engineering study that prioritizes all noise propagation mechanisms participating in the noise attenuation/transmission paths created by helmet mounted hearing defenders. Commercially,