THis standard, together with the most appropriate noise-exposure-forecast (NEF) or locality map available for the airport under consideration, provides guidelines for determining - (a) whether the extent of aircraft noise intrusion makes indoor spaces unacceptable for the activities to be, or being, accommodated; (b) the extent of noise reduction required to provide acceptable noise levels indoors for the types of activity to be, or being, accommodated; and (c) the type of building construction necessary to provide the noise reduction required, provided that windows and doors are closed. The acceptability of outdoor spaces is not covered by this code.