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i <br />Time analyzer were used to measure A-weighted, linear, and octave sound <br />• levels at selected sites. Both were calibrated frequently to ensure a high <br />degree of accuracy. <br />)(~. 3.2 Procedure <br />`" Measurement procedure was similar to that of previous studies. <br />l~ <br />3.2.1 Community Noise <br />a) The Metrosonics analyzer was used at community noise sites M-2 and <br />1`, M-4 (See Maps 1 & 3). <br />" Samples were taken 16 times per second for 24 hours, and were <br /> integrated to derive hourly Leq, L,, L,o, and L90 values. L, <br /> values in conjunction with L,o and L90 values can be used to de- <br />• termine whether intervals of high Leq were caused by loud in- <br /> trusions or an increase in ambient noise. <br />`= b) As done previously, A-weighted, linear, and octave readings were <br />taken to obtain supplementary information for locations M-2 and <br />M-4. If fluctuations in ambient noise levels are detected, spe- <br />~~~'~ cific sources can be isolated according to dominant frequency. <br />L <br />f; <br />3.2.2 Significant Operation Changes <br />Westmoreland personnel indicated that the only significant operations <br />modification that had occurred since September, 1979 was the addition of <br />fan silencers on the baghouse fans on silos 1, 2, and 3. These silencers <br />_ were installed in response to community concerns and have resulted in de- <br />~- <br />• creased sound emissions from those sources. The effects have been particu- <br />~ larly noticeable at site S-3 as noted in Section 4 of this report. <br />,~ <br />