Abstract：
A noise attenuation performance test was conducted on earmuffs using a recoilless weapon launch platform in a confined space, along with two acoustic test fixtures (ATFs). The overpressure at the ATF\'s effective tympanic membrane comprised direct sound at 185 dB sound pressure level (SPL) and reflected sound at 179 dB SPL. Wearing earmuffs reduced these peaks to 162 dB SPL and 169 dB SPL, respectively. The reflected sound from walls was defined as delayed sound. An analytical model for earmuff noise attenuation simulated their effectiveness. The simulation revealed that when the earmuffs attenuated delayed sound, the acoustic impedance of acoustic leakage and the acoustic impedance of the earmuff material decreased by 96% and 50%, respectively. The negative overpressure zone between direct and delayed sound decreased the earmuffs\' fit against the ATF. Additionally, the enclosed volume between the earmuff and the ear canal decreased by 12%. After the installation of bandages on the earmuffs, the overpressure peak of delayed sound was reduced by 5 dB. Furthermore, the acoustic impedance of the earmuff\'s sound leakage path and the acoustic impedance of the earmuff material deformation path increased by 100% and 809%, respectively.
摘要：
在密闭空间内利用无后坐力武器发射平台对耳罩进行了噪声衰减性能试验,随着两个声学测试夹具（ATF）。ATF有效鼓膜处的超压包括185dB声压级（SPL）的直接声音和179dBSPL的反射声音。佩戴耳罩将这些峰值降低到162dBSPL和169dBSPL，分别。从墙壁反射的声音被定义为延迟的声音。耳罩噪声衰减的分析模型模拟了其有效性。模拟显示，当耳罩衰减延迟声音时，声泄漏的声阻抗和耳罩材料的声阻抗分别下降了96%和50%，分别。直接和延迟声音之间的负压区降低了耳罩与ATF的配合。此外,耳罩和耳道之间的封闭体积减少了12%。在耳罩上安装绷带后，延迟声音的超压峰值降低了5dB。此外，耳罩的声音泄漏路径的声阻抗和耳罩材料变形路径的声阻抗分别增加了100%和809%，分别。
