Laserfiche WebLink
DETERMINATION OF REQUIRED STC VALUES <br />Based upon the required Noise Reduction Level (in dBA) and the correction <br />factors noted above, an estimate of the needed STC values can be determined. <br />Standard STC values needed to meet the Metropolitan Council guidelines, based <br />upon the assumptions shown, are listed in Table C-2. <br />TABLE C-2 <br />SPECIFIED REQUIRED STC RATING NEEDED FOR COMPLIANCE <br />NOISE REDUCTION <br />(dBA) Ceiling Walls Windows Doors <br />20 40 40 30 20 <br />25 45 45 35 25 <br />30 50 50 40 30 <br />35 55 55 45 35 <br />40 60 60 50 40 <br />Notes on derivation of values in the table: <br />1. Assumes 74% wall area, 20% window area, 6% door area <br />2. Assumes average room absorption (-4 dB) <br />3. Assumes "standardized" aircraft noise spectrum (15 dB) <br />4. Assumes field installation loss in STC rating (-3 dB) <br />5. Assumes near random angle of incidence (+2 dB) <br />6. Assumes only one wall exposed to exterior noise <br />7. All STC values specified in multiples of 5 db <br />46 <br />