Noise curve
characterisation of background noise
Noise curves are a common way to characterise background noise in unoccupied buildings and spaces. Their purpose is to produce a single-value representation of a complete sound spectrum.
International standards organizations (ISO, ANSI 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. The ANSI/ASA S12.2-2008 standard, for example, recommends an NC value of 25-35 for schools and 15-18 for concert halls.
Background noise may have several undesirable effects. Noise can be an annoyance that creates fatigue and negatively affects productivity, safety and the ability to communicate. Therefore, standard methodologies for quantifying noise have been developed.
Noise curves reflect different standardized means of creating a single number rating for the background noise spectrum in a space. Different rooms, locations, regulations, and applications may allow different acceptable noise ratings.
In most cases, the goal is that background noise should not interfere with the purpose of the room, e.g.
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