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本文描述限幅式通讯隔声耳罩的设计及限幅隔声原理。试验表明:在125～800Hz平均隔声值为27.9dB;在500Hz中心频率,带宽为316Hz的粉红噪声,声级80dBA和75dBA环境下,戴耳罩接收75dB、70dB的单音字,清晰度分别为86.4%和84.4%,不戴则为70%和64.7%;经105dBA主机噪声暴露2h后,10名受试者听力测定,TTS_(2min)平均仅上升3dB,不戴该耳罩则上升26.1dB,其中4000Hz和6000Hz尤为严重,分别上升44dB和37.6dB,实验后第6天才能恢复,用中耳阻抗测定蹬骨肌反射阈变化,亦得到类似结论。温湿度试验表明,在50℃电热恒温水温箱(湿度>95%)和-20℃医用冰箱内各连续试验2h;电路增益仅变化2dB。
This article describes the design of amplitude limiting communication noise earmuffs and limiting sound insulation principle. The results show that the average sound insulation value is 27.9dB at 125 ~ 800Hz, the pink noise with center frequency of 500Hz and bandwidth of 316Hz, the ear cover receives 75dB and 70dB monophonic words under the sound level of 80dBA and 75dBA, the definition are 86.4% and 84.4%, respectively, and 70% and 64.7% respectively. After 10 days exposure to 105dBA host noise, 10 subjects’ hearing test increased only by 3dB at TTS (2min) and increased by 26.1dB , Of which 4000Hz and 6000Hz were particularly serious, rising 44dB and 37.6dB, respectively, after 6 days of experiment to recover, measured by the middle ear impedance pedal muscle muscle reflex threshold change also got similar conclusions. Temperature and humidity test showed that 50 ℃ electric heated water temperature (humidity> 95%) and -20 ℃ medical refrigerator for 2h continuous test; circuit gain only changes 2dB.