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Table 2-4 illustrates the further noise reduction that would be <br />associated with various building types and assuming various <br />window conditions. Note that a conventional building with open <br />windows would further reduce noise levels by approximately 10 <br />dBA. Thus, residences which might be impacted by 55 Ldn levels <br />typically would have a noise level of 45 Ldn on the interior <br />without any special acoustical treatment. <br />TABLE 2-4 <br />NOISE REDUCTION PROVIDED BY A BUILDING <br />Building Type <br />All <br />Light Frame <br />Masonry <br />Window Condition <br />Open <br />Ordinary Sash <br />Closed <br />With Storm Windows <br />Single Glazed <br />Double Glazed <br />*Approximate noise reduction of exterior all <br />window areas. <br />Percent of Exterior Wall <br />Having Open Windows <br />1% <br />2% <br />4% <br />8% <br />16% <br />32% <br />50% <br />Noise Reduction <br />Due to Building <br />Structure (dBA) <br />10* <br />20 <br />25 <br />25 <br />35 <br />having various open - <br />Approximate <br />Noise Reduction <br />17 dBA <br />14 dBA <br />11 dBA <br />8 dBA <br />5 dBA <br />2 dBA <br />0 dBA <br />The analysis determined that no area, other than a portion of the <br />Airport property, would be exposed to 65 Ldn or greater in any of <br />the scenarios. Therefore, according to FAA Order 5050.4, <br />Airport Environmental Handbook, and under MC's guidelines, no <br />further analysis needs to be prepared, and it may be assumed that <br />there would be no significant noise impact. <br />Source: Fundamentals and Abatement of Highway Traffic <br />Noise - U.S. Department of Transportation <br />2-10 <br />