SBIR-STTR Award

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

Army SBIR Topic A04-199 identifies the need for an Active Noise Reduction (ANR) Communication Earplug for Helicopter Crew that, when used in combination with a Gentex HGU-56 helmet, provides “effective attenuation of at least 40 dB at all frequencies, with adequate speech intelligibility, while meeting safety requirements with respect to potential injuries caused by side impacts.” Phase I research has demonstrated total (active+passive) noise reduction of 41-42 dB for sum-of-tones 80-1250 Hz and 25-50 dB for UH-60 cockpit noise 80-2500 Hz using an ANR modified Communication Earplug (CEP) and a hybrid feedforward-feedback ANR algorithm. Phase II research will further develop and evaluate an ANR earplug and associated digital signal processing (DSP) module through systems engineering with integrated cycles of electro-acoustic and mechanical design of the earplug, ANR and communications performance evaluation, and design refinement. Manikin testing, human subject evaluation, field performance, speech intelligibility evaluation, and human factors assessment are primary components of Phase II design and evaluation protocols. A complete design of a product-ready earplug, capable of ANR and communication feedthrough, and an ANR DSP module will be developed. Sound Innovations will deliver 6-10 ANR systems comprised of the ANR earplugs and DSP modules to the U.S. Army and will pursue commercialization for military and civilian markets through Phase III and private funding.

Keywords:
Active Noise Reduction, Lms Filters, Hearing Protection