US Patent 11311068 Sonic wave reducing helmet

A helmet defining an opening for a user's head, the helmet including an outer shell providing a wave guide exit operatively associated with an integrated wave guide layer surrounded by the outer shell, the wave guide layer being adapted to direct sonic waves out the wave guide exit, thereby substantially preventing the sonic waves from penetrating through a remainder of the helmet to the opening. The wave guide layer may be a sonic wave transmission medium composed of acoustic metamaterial, wherein the wave guide layer communicates with the wave guide exit.