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Attenuating Custom Communication Earpiece System

Prototype Description Summary

The ACCES is a customized silicon earpiece poured from individual impressions of the wearer’s external ear. The earpiece contains a miniature receiver embedded deep within the earpiece. Worn under conventional headsets or helmets the product provides comfortable attenuation of high intensity ambient noise (150 dB) while enabling the wearer to hear voice communication and audio signals clearly. Two versions have been developed, one for ground support crew, the other for aircrew.

ACCES is attached via shielded coaxial cable to the communication headsets or aircrew helmet communication line. The attachment is made via connectors which permit easy disconnect so ACCES can be worn alone as hearing protection when noise levels subside to permissible levels. The F-22 Combined Test Force (CTF) and AFRL conducted a highly successful field demonstration with the F-22 ground crew at Edwards AFB. The aircrew version designed for pilots will be flight-tested this summer at Nellis AFB.


Military personnel are exposed to occupational noise intensities far exceeding their counterparts in commercial industry. According to the National Institute of Occupational Safety and Health (NIOSH) 90% of private industry noise is 90 dB (A-weighting) or below. For comparison, U.S. Air Force and Navy personnel supporting jet fighter aircraft are routinely exposed to noise hazards of long duration from 130 to 150 dB (A) which 400 to 600 times more energy than noise at 90 dB. As such, the current hearing protection and voice communication equipment commercially available is grossly ill equipped to accommodate military aviation environments.

Hearing loss compensation from exposure to noise in the military exceeds $300 million annually. Moreover, aerospace operations and personnel can be seriously compromised by inadequate voice communications amongst high ambient noise (100-150 dB (A)). Current military communication headsets are incapable of generating sufficiently intelligible audio signals in this environment. It is therefore critical that military hearing protection and communication headset technology be updated to achieve the necessary combination of hearing protection and voice communication clarity.

ACCES enables all standard military communication headsets and flight helmets to be upgraded economically and easily. No modifications are required to helmets, and only a single wire splice is necessary for the headsets. Following installation, ACCES can be removed without any residual detriment to the helmet or headset. ACCES can be worn alone when noise levels permit use of earplugs only. When noise levels increase and requirements change to double hearing protection, ACCES is then plugged into the helmet or headset, which is worn over ACCES. Double hearing protection is achieved. Once plugged into the headset (for ground support crew) or helmet (for aircrew) common interface with the aircraft intercom is complete.


ACCES eliminates the possibility of poor earplug insertion (as is typical with generic earplugs) as the ACCES earpieces are custom fabricated from impressions made of the users ears. This is significant because as little as 3dB lost protection due to poor earplug insertion can double the wearer’s exposure to noise.

Comfort is superior with custom fit earpieces, affording higher acceptance by users and permitting deeper insertion into the ear canal. Deeper insertion results in increased attenuation (10 dB) over generic earplugs, reducing noise dose by 150% (the dB scale is exponential).

The volume of air trapped between the plug and the eardrum is reduced due to deeper insertion. The result is less trapped air vibration from bone transmission of acoustic energy through the skull (which limits attenuation quality of generic plugs) and more robust speech signal from the miniature loudspeaker in the end of the ACCES earpiece. The signal to noise ratio is significantly improved.

ACCES also provides a solution to the critical need for clear intercom and radio listening under the Nuclear, Biologic, and Chemical (NBC) protection hood. Communication headsets worn over the hood have always been an unsatisfactory situation.


Wherever intercom communication in high noise is required: launch and recovery of aircraft; jet engine run-ups; engine test cell operations; rocket engine tests; air base security forces; aircraft cockpits; loadmaster operations; ground forces on radios deployed in NBC protection; ground forces operating tanks and mechanized vehicles; aircraft carrier operations; navy power plant operations.

ACCES delivers improved speech intelligibility (as verified by Edwards AFB) in high intensity ambient noise environments while simultaneously providing increased protection against noise induced hearing loss. Controlled lab tests of ACCES speech intelligibility performance currently are under way at the Air Force Research Laboratory, Wright-Patterson AFB.

Capt John Hall
DSN 785-3660 ext. 419
Human Effectiveness Directorate,
Crew System Interface Division, Aural Displays & Bioacoustics Branch
Wright-Patterson AFB, OH.

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