SBIR-STTR Award

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 of earplugs 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 all specific 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 principles in 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 performance measurements, will help to identify the absolute best possible noise attenuation that can be achieved in the occluded space, not accounting for bone conduction paths.

Benefit:
The most significant benefit of the Phase I program will be the contribution of a detailed acoustic engineering study that prioritizes all noise propagation mechanisms participating in the noise attenuation/transmission paths created by helmet mounted hearing defenders. Commercially, the FEA models developed under this Phase I program will be made available to both Navy engineers and sold to other noise control designers who wish to upgrade their design methods. The FEA models will have to be evaluated using the ANSYS software but the specific earcup FEA models can be provided easily as a commercial product provided that the recipient has purchased ANSYS software.

Keywords:
Noise control, Noise control, Finite Element Analysis, Hearing defenders, Test-model correlation, Earcups, Earplugs

A Finite Element-Based Acoustic Engineering Design Program for Advancements in Passive Noise Reduction Performance of Helmet Mounted Noise Defenders Abstract The use of finite element analysis (FEA) modeling techniques to model both single hearing protection and double hearing protection noise attenuation will be refined during this Phase II program. Physically realistic, three-dimensional models of circumaural earcups and custom PVC earplugs will be created using the ABAQUS FEA software and coupled to fluid models of the ear canal geometries for a variety of users. The FEA model results will be made available for comparisons to MIRE test data acquired for both single and double hearing protection device (HPD) combinations of the earcup and earplug devices. This project extends the successful Phase I project which initiated first-generation FEA model results. Those results were validated using experimental determinations of material transmission loss, vibration testing, and testing of both structural-acoustic and interior acoustic responses for the HPD configurations. The ultimate goals for the Phase II FEA modeling program are to finalize prioritization of all noise attenuation mechanisms and to utilize the FEA models for identifying advanced state-of-the-art performance for HPD’s. Benefit The anticipated benefits are the creation of a modeling data base the U.S. Navy can use for future considerations of proposed revisions to circumaural headsets. The development of accurate FEA models will allow computational modeling, versus more expensive experimental investigations, of headset innovations proposed in future years. This will be a substantial cost savings to the government. State-of-the-art headset technologies will be identified using the FEA modeling tools. Keywords Finite Element Analysis, communication headset, Double Hearing Protection, Noise Attenuation, Jet noise, single hearing protection