Design of Acoustic Metamaterials for Passive Hearing Protector

We propose to develop new acoustic metamaterials (AMMs) using locally resonant regimented structures, suitable for application in Hearing Protector Devices (HPDs), that will act as frequency selective acoustic filter for hearing protection. Our computational simulations conducted in phase I project have demonstrated that significant acoustic attenuation can be achieved in desired frequency ranges (band gaps) using novel structures of perforated, membrane based and solid inclusion materials. In phase II we propose to adapt our multiphysics computational software as CAD tools for AMMs and use them to design optimized structures and HPD devices that achieve more than 12 dB attenuation at high audible frequencies (>3 kHz) and low attenuation (<1 dB) at frequencies low frequencies (<1 kHz). The main goal is to establish robust fabrication processes of selected classes of AMMs and their packaging into suitable HPDs. Several samples of AMMs will be fabricated and tested in laboratory experiments using both acoustic and shock wave fields. Prototype HPDs will be tested using human head and ear phantoms for military environment acoustic signatures such as helicopter cabin, aircraft carrier deck, rifle range, breachers test etc. In a partnership with US industrial manufactures we will fabricate a batch of devices suitable for human and field testing.