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Investigation of hearing ability of divers in hyperbaric helium-air mixture environment in submergence

高压氦气混合环境下潜水员浸没听力能力调查

基本信息

批准号：
03650274
负责人：
SUZUKI Hisayoshi
金额：
$ 1.47万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

1. Frequency characteristics of six kinds of headphones were measured at ambient pressures of 1ATA to 31ATA. A YAMAHA HP-1 was best suited for the present purpose because its frequency characteristics were stable even at the high ambient pressures. 2. The minimum-audible sound pressure level (MAP) and the equal-loudness contours (ELC) were measured at 1ATA to 31 ATA with an audiometer RION AA-71. To prevent the background noise, the headphone unit of HP-1 was build in an ear-protector. MAPs in normal air and at 5 meter depth were properly measured. Since the lower frequency noise could not be reduced by the ear-protector, MAPs at deeper than 20 meter were measured only at higher frequency than 1.5KHz. ALCs were widely changed by the ambient preesures. The curve of ALC at deeper than 120 meter were looked like a letter "w", showing that ALCs have local minima at 2KHz and 6KHz, and a peak at 3KHz. 3. The bone-conduction hearing thresholds (BCT) were also measured. The variation of BCT by the ambient pressure was less than that of MAP. Using an electronic circuit modeling of the ear canal, a shift of peak frequency of MAP in hyperbaric pressures was partly reasoned by change in acoustic trans-mission character of the ear canal. 5. The sound absorption coefficients of three absorber materials were measured at hyperbaric N_2-air and He-air. The curves of absorption coefficients were shifted to higher frequency region. In other words the sound absorption coefficient were reduced in hyperbaric pressure. It was found that the frequencies at which the absorption coefficient remains unchanged were proportional with the exponent of the product of gas density and cubic power of velocity. The exponents are 0.7 for glass wool, 0.5 for felt, and 0.7 for absorption sponge. 6. We have implemented a helium speech database on a personal computer.At present, there are 3,000 data recorded with phoneme label.

1.在1ATA ~ 31 ATA的环境压力下，测量了6种耳机的频率特性。YAMAHA HP-1最适合于本目的，因为它的频率特性即使在高环境压力下也是稳定的。2.使用RION AA-71听力计测量1ATA至31 ATA的最小可听声压级（MAP）和等响轮廓线（ELC）。为了防止背景噪音，HP-1的耳机单元内置在护耳器中。正常空气中和5米深度的MAP被适当地测量。由于护耳器不能降低低频噪声，因此仅在高于1.5KHz的频率下测量了20米以下深度的MAP。环境压力对ALC的影响很大。120米以上的ALC曲线呈“W”形，在2KHz和6 KHz处有局部极小值，在3 KHz处有一峰值。3.同时测定骨导听阈（BCT）。BCT随环境压力的变化小于MAP随环境压力的变化。利用耳道电子电路模型，分析了MAP峰值频率在高压下的移动，部分原因是耳道声传输特性的改变。5.在高压N_2-空气和He-空气中测量了三种吸声材料的吸声系数。吸收系数曲线向高频移动。也就是说，在高压下，吸声系数降低。结果表明，吸收系数保持不变的频率与气体密度和速度的三次方乘积的指数成正比。玻璃棉的指数为0.7，毡的指数为0.5，吸收海绵的指数为0.7。6.我们已经在个人计算机上实现了氦语音数据库，目前有3,000个带有音素标记的数据。