Davis Rickie R, Shaw Peter B
Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Columbia Parkway, Cincinnati, OH 45226, USA.
Noise Health. 2011 Mar-Apr;13(51):93-8. doi: 10.4103/1463-1741.77200.
A major barrier to effective wear of hearing protection is comfort. This study examined several comfort indicators in the earmuff-type hearing protectors. Twenty subjects wore hearing protectors instrumented with two different temperature/humidity measurement systems (Omega and iButton) while walking a corridor for about 25 min. The instruments recorded the temperature and humidity every 10 s and their results were compared. In addition, skin surface pH was measured at the ear canal entrance before and after the task. Finally, the subject indicated earmuff comfort at the beginning and end of the session. Earmuff comfort decreased significantly over the course of the walking task. Ear canal pH became slightly less acidic, but the change was not statistically significant. The two temperature/humidity systems provided comparable results. Heat increased at about 0.3°F while humidity built up at about 0.5%/min. However, the study found some limitations on the instrumentation. The complexity of the electrical connections and equipment in the Omega probe system led to loss of three subject's data. The iButton device was more robust, but provided only 256 gradations of temperature and relative humidity. Even with its limitations, the iButton device would be a valuable tool for field studies. The present study showed that the buildup of heat and humidity can be modeled using linear equations. The present study demonstrates that relatively inexpensive tools and a low-exertion task can provide important information about the under-earmuff environment, which can inform assumptions about comfort during use.
有效佩戴听力保护器的一个主要障碍是舒适度。本研究考察了耳罩式听力保护器的几个舒适度指标。20名受试者佩戴配备了两种不同温度/湿度测量系统（欧米茄和iButton）的听力保护器，在走廊行走约25分钟。仪器每10秒记录一次温度和湿度，并对结果进行比较。此外，在任务前后测量耳道入口处的皮肤表面pH值。最后，受试者在实验开始和结束时表明耳罩的舒适度。在行走任务过程中，耳罩舒适度显著下降。耳道pH值酸性略有降低，但变化无统计学意义。两种温度/湿度系统提供了可比的结果。热量以约0.3华氏度的速度增加，而湿度以约0.5%/分钟的速度累积。然而，该研究发现了仪器方面的一些局限性。欧米茄探头系统中电气连接和设备的复杂性导致三名受试者的数据丢失。iButton设备更坚固，但仅提供256个温度和相对湿度等级。即使有其局限性，iButton设备对于实地研究仍是一个有价值的工具。本研究表明，热量和湿度的累积可以用线性方程建模。本研究表明，相对便宜的工具和低强度任务可以提供有关耳罩下环境的重要信息，这可以为使用过程中的舒适度假设提供依据。
