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.

使用头状声学测试夹具在漫射宽带噪声场中的三分之一倍频程中测量了四对耳罩的插入损耗，其中包括一个降噪耳机。声学测试夹具包含真实的耳朵模拟器，在鼓膜位置带有麦克风。插入损耗的测量是 (i) 单独使用耳罩，(ii) 将耳罩戴在防闪光罩上，以及 (iii) 对于一只耳罩，耳罩戴在罩下。其他三个耳罩无法安装在引擎盖下。还测量了防闪光罩自身的插入损耗。在耳罩下戴防闪光罩大大降低了对噪音的防护，高频降低了 20-23 dB，中频降低了 17-20 dB，低频降低了 12-16 dB，总体降低了 16-20 dB . 只有一个耳罩足够纤薄，可以放在防闪光罩下。在这个耳罩上戴上防闪光罩对耳罩插入损耗的影响只有 1 dB 的数量级。如果可以将防闪光罩设计为适合其他类型的耳罩和耳机，那么这些耳罩和耳机的保护实际上将得到维持。