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-27- <br />easily be complied with using measuring devices and visual <br />inspection of the measurement site. <br />subpart 4, item B requires that measurements must be made <br />using the A -weighting and fast response characteristics of the <br />sound measuring device as specified in the American National <br />Standard Institute S1.4-1983. The A -weighting more closely <br />resembles the human ears response to sound. Using these <br />characteristics to measure environmental noise has long been <br />established as an acceptable method in the acoustical field and <br />therefore it is reasonable to incorporate them into this rule. <br />Subpart 41 item c requires that measurements must not be made <br />in sustained winds greater than 12 miles per hour or in <br />precipitation. Microphones used on measuring devices will <br />measure the noise of the wind once the wind velocity reaches <br />about twelve miles per hour. Also, precipitation interferes with <br />electrical conditions of the measuring devices. Therefore these <br />requirements are needed to protect the accuracy of sound level <br />measurements. These requirements are reasonable because they can <br />easily be complied with using a wiiid velocity measuring device <br />and visuAl inspection of the measurement site. <br />Subpart 41 item D requires that measurements must be made <br />using a windscreen. A windscreen is primarily a protective <br />device; however, it does reduce effects on the microphone that <br />may result from low velocity winds (less than 12 miles per hour). <br />It is reasonable to require the use of a windscreen to protect <br />