This standard is the second in a proposed series of parts concerning description and measurement of outdoor environmental sound. This standard describes recommended procedures for measurement of long-term, time-average environmental sound outdoors at one or more locations in a community for environmental assessment or planning for compatible land uses and for other purposes such as noise prediction validation and regulation. Sound may be produced by one or more separate, distributed sound sources such as a highway, factory, or airport, or by all contributing sound sources. For spatial or temporal samples of environmental sound in a community, requirements are given for the number of sound-measurement locations and the duration of the sound-sampling intervals needed to obtain average values for long-term environmental sound levels that are within stated accuracy limits for Class A, Class B, or Class C measurements. The purpose of this standard is to provide for a commonality for measurements of outdoor environmental sound as it may affect people in and around dwellings.