Hearing protection: Surpassing the limits to attenuation imposed by the bone-conduction pathways

摘要: With louder and weapon systems being developed military personnel exposed to steady noise levels approaching sometimes exceeding 150 dB, a growing interest in greater amounts of hearing protection is evident. When the need for communications included equation, situation even more extreme. New initiatives are underway design improved protection, including active reduction (ANR) earplugs perhaps cancellation head-borne vibration. that mind it may be useful explore limits attenuation, whether they can approached with existing technology. Data on achievable high-attenuation foam earplugs, as function insertion depth, will reported. Previous studies reviewed provide indications bone-conduction (BC) attenuation that, terms mean values, range from 40 60 dB across frequencies 125 Hz 8 kHz. Additionally, new research effects flight helmet BC limits, well potential deeply inserted passive worn earmuffs, or active-noise examined. The data demonstrate gains 10 above head-not-covered achieved if head effectively shielded acoustical stimulation.