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Active Noise Reduction HGU-56P Aviator Helmet



OBJECTIVE: Reduce noise and improve speech intelligibility with least weight increase to HGU-56P Aviator Helmet

DESCRIPTION: Improved speech intelligibility is a fundamental component of soldier lethality, one of the six army modernization priorities of the Army which includes the core requirement of communication.Army aviation has relied on noise cancelling microphone technology based on performance specification MIL-PRF-26542F for over 20 years.Naval aviators have relied on active noise reduction (ANR) earcups with the same microphone based on performance specification MIL-E-29581 for over 20 years.The Army never adopted the ANR system because the Navy specification calls out Rigid Earcups (paragraph which violates the requirement for impact protection in the ear dome to prevent basilar skull fractures.The ANR earcup was considered too heavy and rigid for integration into the HGU-56P.Active noise reduction technology has improved and the electronics for achieving better speech intelligibility has shrunk dramatically since the original Navy specification was released.Commercial headsets commonly used on jets and rotary wing aircraft which incorporate ANR include the Lightspeed Zulu 3 Aviation Headset - GA Plugs: A20 Aviation Headset: Clark DC PRO-X2: among these and other headsets designed to address better passive and active noise reduction include better ear cups which allow sealing the ears even when wearing eyeglasses, lighter weight, reduced size, improved active noise cancellation, automatic gain control, and active equalization.In addition, modern aviation headsets include either a standard interface audio jack or Bluetooth allowing commercial phones to be used while in flight without taking off the headset, something else not core but desired.This solicitation intends to identify an existing commercial solution to provide the best overall reduction in ambient noise reaching the user’s ears while improving speech intelligibility.Threshold improvement requirement is 10% over current sound attenuation of the HGU-56P Aviator helmet.Objective is 30 decibels of noise reduction average across frequencies without removing speech from user as side effect.According to the Department of Veterans Affairs, hearing problems such as tinnitus are described by the VA as among “the most prevalent service-connected disability among American Veterans.”Improved hearing protection can not only improve communication, it can reduce hearing loss and the cost of long term veterans benefits paid to our service members.

PHASE I: This effort shall identify and test the most promising combination of passive and active noise reduction technology that can be retrofit into the HGU-56P aviator helmet at the least weight and cost.The initial proposal shall identify a solution which provides noise reduction data showing acoustic attenuation of the technology proposed by comparison to paragraph 3.4 of MIL-E-29581 earcup and MIL-PRF-26542F microphone (if proposal includes replacement of microphone).The contractor shall perform a laboratory demonstration in Phase I demonstrating and quantifying noise reduction and speech intelligibility improvement in benchtop tests using two Government furnished HGU-56P helmets.The contractor shall modify one of the helmets with the proposed improvements and perform identical tests using one modified and one unmodified HGU-56P helmet so that comparison data clearly shows performance improvements achieved.Noise reduction shall be measured using a probe microphone method (REAT Method is not allowed).A report shall be provided which details the tests performed and the improvement demonstrated.Speech intelligibility shall be evaluated using the Modified Rhyme Test method (ANSI S3.2-1989).A Noise Reduction Rating shall be produced IAW ANSI S3.19-1974.The contractor shall document changes to the existing earcup and/or microphone specifications which definitize performance improvement.The report shall estimate costs and weight impact of the technology solution proposed.Measurement of real-ear attenuation of hearing protectors shall be performed IAW ANSI S12.6.The current sound attenuation of the HGU-56P aviator helmet when tested IAW ANSI S12.6 is as follows:Frequency (Hz) 125 250 500 1000 2000 3150 4000 6300 8000 Attenuation (Decibels) 17 14 20 21 26 38 37 44 42

PHASE II: The solution identified in phase I will be applied and tested to meet all requirements of the specifications proposed for update or replacement.As example, if a replacement earcup is proposed, the existing ear cup specification (MIL-E-29581) would serve as a starting point for a new ear cup specification.Likewise, if the microphone is proposed to be replaced, the microphone specification (MIL-PRF-26542F) would serve as a starting point for a new microphone specification.The contractor shall propose written changes for any existing hardware specifications associated with hardware being changed or replaced.All testing shall be performed IAW the updated hardware specifications submitted by the contractor.A summary report at the end of the test shall document all performance improvement of the new solution to include capabilities added to the performance specifications identified in Phase I.If testing shows initial projections of performance differ from actual results, the contractor shall update any product specifications being replaced or updated as necessary.The contractor shall perform bench testing for all ear cup specification requirements on production representative prototypes if the ear cup is being modified/replaced with an earcup equipped with ANR IAW a contractor proposed update or replacement of MIL-E-29581.The contractor shall perform bench testing for all microphone specification requirements on production representative prototypes if the microphone is being modified/replaced with an improved noise cancelling microphone IAW a contractor proposed update or replacement of MIL-PRF-26542.The contractor shall build sufficient quantities of noise reduction solutions and retrofit Government furnished HGU-56P helmets to account for testing all performance requirements in the updated specifications.The new noise reduction system shall be capable of being retrofit into the HGU-56P helmet without special tools.Objective of the replacement solution is to be capable of installation as direct part swap for original component(s).The ANR solution shall be capable of accepting power between 3 and 5V DC for operation.Deliverables will include test plan, test report, updated performance specification(s) reflecting measured improvement in audio performance, minutes for all meetings conducted with the vendor, presentation slides for test readiness review, a white paper detailing the installation cost of the retrofit solution, and a cost report detailing manufacturing cost as a function of helmet quantity from a minimum of 50 and up to 1000 at a time.TRL: (Technology Readiness Level) TRL Explanation Biomedical TRL Explanation TRL 6 - System/subsystem model or prototype demonstration in a relevant environment

PHASE III: Develop production processes and implement any design changes required to optimize components for retrofit into HGU-56P helmet.Update any specifications needed to reflect final production configuration weight and performance.Repeat bench qualification testing if production configuration deviates too far from prototype configuration tested in Phase II.Support operational testing on multiple Army rotary wing aircraft.Aviation helmets used throughout DOD may find retrofit application for this same solution.Most aviation headsets are designed for fixed wing applications (quiet cockpits) due to their greater density in commercial applications (moving people and cargo).This solution will be optimized for rotary wing applications which are far louder, and will therefore have commercial applications in both commercial helicopters, service and maintenance activities around operational aircraft on runways, motorcycles, and the racing industry where engine noise is very loud.

KEYWORDS: Active Noise Reduction, Acoustic Noise Reduction, Passive Noise Reduction, Speech Intelligibility



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