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-0 <br />the measurement devices from debris and to reduce inaccuracies in <br />the measurement due to low velocity winds. <br />Subpart 5 sets forth methods for deterimination of the hourly <br />Leq. All sound level measuring devices are capable of measuring <br />hourly Leq; however, some devices require manual calculations, <br />whereas other devices can make calculations automatically. For <br />both manual and automated measuring devices the basic <br />mathematical formula for the determination of the Leq is the <br />same, but the method of determining the Leq for an hour may <br />differ. Because of this, it is reasonable to provide methods for <br />determination of hourly Leq to assure that the measurement is a <br />reliable one. It <br />Subpart 5 includes items A through C, which are discussed <br />below. <br />Subpart 5, item A provides that hand held measuring devices <br />(manual devices) must use the check -of:: method described in <br />FHWB-DP-45-1R, Section 3.6. This methcd describes a <br />statistically based procedure where measurements are taken every <br />ten seconds until a statistical sample has been collected. Once <br />a statistical test is performed and specific criteria are met, <br />then the measurement is completed. This procedure is reasonable <br />because it provides for a statistically verified hourly Leq and <br />allows non -automated sound measuring devices to be used. In <br />addition, this method is currently used by the Agency, has been <br />