International standards organizations (ISO,[2] ANSI[3] and ASA) recognize the need to objectify judgements on the amount of ambient noise in enclosed spaces, and provide us with definitions for various noise curves.
Noise can be an annoyance that creates fatigue and negatively affects productivity, safety and the ability to communicate.
Different rooms, locations, regulations, and applications may allow different acceptable noise ratings.
The result is determined by the lowest curve which is not touched by the measured spectrum at any position in the audio frequency range.
Noise curves serve as uniform measuring standards and are referred to by many noise regulations covering a variety of locations from concert halls, rock concerts, lecture rooms and offices to clay target shooting ranges.