An Active Noise Reduction Communication Earplug for Helicopter Crew

This Phase I SBIR research develops a prototype active earplug and hybrid feedforward-feedback active noise control (ANR) algorithm to provide at least 40 dB noise reduction over all frequencies when used in conjunction with a Gentex HGU-56 helmet. Ear insert hardware will be fabricated from an existing communication earplug (CEP), and an existing hybrid ANR algorithm, used in prior ANR research for circumaural earcups, will be modified for the earplug. The ANR algorithm is implemented on a DSP development system for rapid design and optimization of feedforward and feedback components. The feedforward ANR component is based on the investigator's patented Lyapunov tuning method, which provides excellent stability and noise reduction performance for both stationary and non-stationary noise sources. Prototype hardware and hybrid ANR algorithms will be evaluated through flat plate testing and using a HEAD Acoustics manikin. Experimental evaluation will determine ANR algorithm stability margins and performance with respect to noise source characteristics with and without communication feedthrough. Phase I option tasks provide an initial assessment of communication and speech intelligibility and initiate development of an autonomous ANR module prototype for flight testing early in Phase II.