A single-number noise rating system published in 1957 to rate steady-state continuous noise in a room from all types of equipment, including fans, mixing boxes, diffusers, etc.
Noise criteria curves evaluate existing listening conditions by measuring sound levels (preferably at ear level) at the loudest locations in a room. Noise criteria may also be referred to dBA levels.
In acoustics, normally used to describe a rating system for evaluating noise from heating, ventilating and air conditioning ( HVAC) systems. It has come to be used as a basis for evaluating and establishing requirements for background noise in listening spaces. Based on a set of sound level vs. frequency curves known as the NC criteria. The lowest curve that the spectrum of the measured sound does not exceed is defined as the noise criterion (e.g. NC-30) for that room. There are other variations on this theme, adopted for different purposes, or in different parts of the world (e.g. NR - noise rating - in Europe).
Noise criteria curves used to evaluate existing listening conditions at ear level by measuring sound levels at the loudest locations in a room. NC criteria can be referred to equivalent dBA levels.
Sometimes referred to as "dBA levels," it is used to assess listening conditions at ear level by gauging sound levels at loudest locations in a room.
A one-number rating for the quietness of a room. Typically associated with HVAC noise but includes all ambient noise present in room when measured. Examples of typical NC ratings: Below NC 15: Quiet studio NC 15 - NC 25: Quiet library or classroom NC 25 - NC 35 Typical Office NC 35 - NC 45 Noisy Office
A way for an architect to specify the maximum permissible sound power level in each of the eight octave bands NC curves give. In a graphical form, maximum permissible intensity per octave band.