Design of Acoustic Metamaterials for Passive Hearing Protector

CFDRC proposes to develop new acoustic metamaterials, more specifically Locally Resonant Sonic Materials (LRSM), to be used in passive Hearing Protection Devices (HPD). LRSM derive their unique properties from resonators contained within each unit cell. Sound attenuation of finite size of LRSM is determined by the interaction of an incident elastic pulse with the resonators within the unit cells. The components that correspond to the resonance frequencies excite the resonators, taking its energy out of the propagating pulse. This trapped energy is then gradually passed to the surrounding material. The direction of the waves emitted by the resonant vibrations is in general different from the direction of the incident pulse, yielding a net attenuation of these frequency components. We can tune the band gaps of the LRSM response by varying the size and geometry of the structural unit. To accomplish the design objective, CFDRC proposes to use our existing software toolkit as a tool to design the optimum LRSM for HPD in Phase I. We will use existing modules as well as adding new modules to suit the needs for LRSM design. We plan to incorporate our existing auditory computational model to virtually test conceptual HPD designs using the LRSM.