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A safety criterion for pressure waves incident from the front was worked out on the bases ofnumerous animal experiments and ample verification in practical exposure cases in maneuvers withvarious weapons.The proposed safety criterion is expressed as p=177-6 long T.N,where p is thepeak pressure in dB re 2×10~(-5)Pa,T——impulse duration in ms,and N——number of roundson one exposure day.This safety criterion has been proved efficient in protecting 90% or moreof the exposed personnel from pressure wave injury.For normal incidence on the ear,p shouldbe decreased by 5 dB. 相似文献
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本工作研究了在一次持续百余天的模拟试验中强噪声(95—110分贝,每天8小时)、高室温(35℃)等环境因素对人听觉功能的影响.9名受试者在进入模拟环境后,听力在30多天时下降最多达25—35分贝,以后即趋于稳定.音调辨别阈△F在60天后才开始增大,并有随时间而继续增大的趋势.响度辨别阈、声源定位误差、短期记忆正确率等在整个试验中均无明显的规律性变化.在离开模拟环境后,听力和△F在数天至一月内完全恢复正常.试验结果表明,所给的环境条件对人听觉功能的影响是暂时性的.文中讨论了环境因素对神经系统总功能状态的影响及其评定问题. 相似文献
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Evoked potential recorded from the guinea pig auditory cortex in response to high-intensityclicks was found to be systematically augmented as a result of exposure to noise in appropriatedosage which caused a moderate temporal response-threshold shift(16—48 dB,5—20 min afterexposure).The maximum post-exposure response amplitude might exceed the pre-exposure valueby 30—120%.No parallel amplitude increment was observed in cochlear potential and in evokedpotentials from the medial geniculate body,a fact indicating the cortical site of the mechanism under-lying such augmentation. 相似文献
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