主动降噪耳机防护强脉冲噪声性能的实验研究

The Assessments of the Performance of Noise Cancelling Hearing Protection Devices Undergoing the High-level Impulse Noise

目的对两款新型主动降噪技术耳机能否有效防护强脉冲噪声进行初步探索。方法在标准声场内使用火花发声器模拟脉冲噪声，将主动降噪耳机佩戴在人工头上进行测试。首先测量人工头无降噪设备条件下脉冲噪声值5次，作为基线水平；再对两款耳机处于关闭、最低档和最高档状态下，人工头佩戴主动降噪耳机后脉冲噪声值分别进行5次测量，取平均值，纳入统计分析。结果人工头测试脉冲噪声值基线水平为132．3dBSPL；两款主动降噪耳机关闭被动降噪状态下平均降噪水平分别为29．2dBSPL、31．9dBSPL，主动降噪能力处于最低水平时平均降噪水平分别为26．82dBSPL、27．9dBSPL，最高水平时平均降噪水平分别为29．9dBSPL、32．0dBSPL，组间比较，差异具有统计学意义（P〈0．001）。结论主动降噪耳机针对脉冲噪声的主动降噪水平优于单纯的被动降噪水平。

Objective The aim of the study is to test the performance of active noise cancelling （ANC） in the two new hearing protection devices （HPDs） for impulse noise. Methods We put a spark generator for impulse noises in the sound field where the HPDs are worn on the artificial head. The means of the peak sound pressure levels measured 5 times serves as the baseline. Two types of ANC earmuffs are worn on the artificial head and respectively take the measurement at the closed, the lowest and the highest grades for 5 times. Results The average maximal pressure of the spark is 132.3 dB SPL. The average acoustic insulation of two ANC hearing protection in closed grade is 29.2 dB SPL and 31.9 dB SPL.Those at the lowest grade are 26.82 dB SPL and 27.9 dB SPL. Those at the lowest grade are 29.9 dB SPL and 32.0 dB SPL. The comparisons between the groups shows the difference （P=0.001） is statistically significant. Conclusion The ANC hearing protection devices are more effective than the passive ones in attenuation of impulse noise.