Institute of Naval Medicine, UK.
ISVR Consulting, University of Southampton, UK.
Ind Health. 2021 Sep 9;59(4):204-219. doi: 10.2486/indhealth.2020-0103. Epub 2021 Mar 11.
The insertion losses of four pairs of earmuffs, including one noise-excluding headset, were measured in one-third octave bands in a diffuse broadband noise field using a head-like acoustic test fixture. The acoustic test fixture contained realistic ear simulators with microphones at the eardrum positions. The insertion losses were measured (i) with the earmuffs on their own, (ii) with the earmuffs worn over an anti-flash hood, and (iii) for one earmuff, with the earmuff worn under the hood. The other three earmuffs could not be fitted under the hood. The insertion loss of the anti-flash hood on its own was also measured. Wearing an anti-flash hood under the earmuffs greatly reduced the protection against noise, by 20-23 dB at high frequencies, by 17-20 dB at middle frequencies, by 12-16 dB at low frequencies, and by 16-20 dB overall. Only one earmuff was slim enough to fit under an anti-flash hood. Wearing an anti-flash hood over this earmuff had only a marginal effect on the earmuff insertion loss, of the order of 1 dB. If anti-flash hoods could be designed to fit over other types of earmuffs and headsets, the protection of these earmuffs and headsets would be virtually maintained.
在漫射宽带噪声场中，使用类似于头部的声学测试夹具，在 1/3 倍频程带宽内测量了四副耳塞（包括一副隔音耳机）的插入损耗。声学测试夹具包含具有麦克风的逼真耳模拟器，位于鼓膜位置。插入损耗的测量方法如下：（i）耳塞单独佩戴时，（ii）耳塞佩戴在防闪光帽上时，以及（iii）对于一副耳塞，耳塞佩戴在帽子下时。其他三副耳塞无法戴在帽子下。单独的防闪光帽的插入损耗也进行了测量。在耳塞下佩戴防闪光帽会大大降低对噪声的保护，在高频时降低 20-23dB，在中频时降低 17-20dB，在低频时降低 12-16dB，总体降低 16-20dB。只有一副耳塞足够薄，可以戴在防闪光帽下。在这副耳塞上戴防闪光帽对耳塞插入损耗的影响微乎其微，约为 1dB。如果可以设计出适合其他类型耳塞和耳机的防闪光帽，这些耳塞和耳机的保护将几乎得到保持。
