<p> Personnel who work on the flight deck of an aircraft carrier are exposed to extreme levels of jet engine noise often in excess of 140 decibels (dB). The current circumaural hearing protective devices (CAHPD) employed by flight deck crewmen are inadequate for the level of protection required for these extreme levels of noise. Fiber-reinforced thermoset polymer composite (FRPC) materials such as aramid fibers used in body armor, have high theoretical values of acoustic impedance due to a fundamentally high modulus of elasticity and may offer a superior level of hearing protection over original equipment (OE) thermoplastic CAHPDs. The objective of this project was to measure and evaluate the attenuation of CAHPD’s constructed from FRPC materials. FRPC CAHPD ear cups were paired with OE thermoplastic CAHPD ear cups of equal shape and thickness, and the protected and unprotected A-weighted sound pressure level (SPL) was measured in continuous and impulse noise environments >80 dBA using a JOLENE manikin. These data were evaluated for paired differences between the protected and unprotected mean SPL, and OE protected and FRPC protected mean SPL and indicates that OE thermoplastic CAHPDs provide greater sound attenuation of continuous noise >80 dBA and aramid FRPC CAHPDs provide greater sound attenuation of impulse noise >80 dBA.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:1595804 |
| Date | 12 August 2015 |
| Creators | Augustine, Steven |
| Publisher | University of South Florida |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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