The infrasound generated from certain equipment has great physical and psychological influence on operat-ing personnel. Through a detailed acoustic measurement and systematical data analysis, and by taking into account physical and psychological characteristics of the infrasound, an infrasound field improvement method is proposed. The proposed method is based on analyzing the theoretical defects of the"common position resonance method"which also leads to great discrepancy between experimental and actual states. The comparative experiments of insulation sound are carried out in different conditions, such as with and without sound absorption inside sound insulation cabin, float mounting of test cabinet, with and without sound absorption inside test cabinet. Testing parameters include sound level and acceleration. Experimental results show that the proposed sound insulation method achieves a 15~20dB noise re-duction in frequency band from 20 to 40Hz, which meets well with the anticipated.

Objective To develop a simulation device of infrasound field in the cabin of a certain naval boat .Methods Through detection of the infrasound pressure levels and noise spectrum on the deck and in the cabins and analysis of the infrasound field radiation, the principle of secondary infrasound induction was thus obtained .Results The simulation device that complied with real boat infrasound environment was developed successfully .Conclusion The infrasound field generated by the simulation device coinci-ded with the real boat infrasound environment , which could provide basic support for the development of control measures and assess -ment of control effects .

Objective To study the effect of distortion product otoacoustic emission (DPOAE) on guinea pigs exposed to narrow band noise of different intensity. Methods Sixty healthy male guinea pigs were randomly divided into 3 groups: the 105 dBA group, the 110 dBA group and the 115 dBA group. The duration of exposure for all the groups was 3 hours and noise spectrum was narrow - band, with a mid - frequency of 4 000Hz and band-width of 1000 Hz. Two days before and 15 minutes after noise exposure, DPOAE of guinea pigs was measured by means of Smart OAE Hearing Test System. Results With increased intensity in noise exposure, DPOAE amplitude and throughput of guinea pigs at all the distortion frequencies showed a decreased tendency. For the 105 dBA group and the 110 dBA group at the distortion frequency of 1 409 Hz, and for the 105 dBA group and the 115 dBA group at frequencies of 499 Hz,704 Hz,1 003 Hz, and 1 409 Hz, the difference in DPOAE amplitude and throughput after exposure all had statistically significance (P<0.05). Conclusions Following exposure to 4 000Hz narrow band noise, DPOAE began to change at high frequencies and heating damage extended from higher frequency to lower frequencies as noise level increased.

目的 筛选一种噪声暴露方案,以便较好地区分听觉损伤易感豚鼠和不易感豚鼠.利用该噪声暴露方案建立噪声听觉损伤模型,在此基础上确定易感与不易感豚鼠,为进一步开展易感性相关基因研究提供便利.方法 60只雄性健康豚鼠(体重280～320 g)随机平均分为3组,分别为A方案组(105 dBA噪声暴露)、B方案组(110 dBA噪声暴露)、C方案组(115 dBA噪声暴露).评价各方案区分易感与不易感豚鼠的效能,确定最佳方案.利用该方案建立噪声听觉损伤模型,利用百分位数的方法确定噪声听觉损伤易感与不易感豚鼠.结果 B方案组和C方案组豚鼠TTS分布的离散程度无明显差异,但均大于A方案组.模型建立中,数据成左偏态分布,利用百分位数确定了易感与不易感豚鼠.结论 B方案更适合于建立筛选用的豚鼠噪声听觉损伤易感模型.

Based on the results of noise reduction in a control room,treatment principle and design procedure of noise control are presented.With proper distribution of main noise sources,their constitutes are analyzed.Successful techniques including shock absorption,sound insulation,sound absorption,etc.are used to improve low frequency environmental noise.The final test shows that SPL is reduced by 19dB.The peak has been reduced by 26dB at 125Hz.Coal grinding machines are found to be the main noise sources,with average sound pressure levels more than 95dBA.It is concluded that the control room should be properly designed according to the sound pressure levels and the workshop conditions.