Noise Measurement is carried out in various fields. In acoustics, it can be for the purpose of measuring environmental noise, or part of a test procedure using white noise, or some other specialised form of test signal. In electronics it relates to the sensitivity of communications systems, the purity of signals, or the quality of audio systems. The concept is to define the noise level below which signals cannot reliably be detected. It can be thought of as uncertainty of the information being carried over a communications channel. In audio systems and broadcasting specific methods are used to obtain subjectively valid results in order that different devices and signal paths may be compared regardless of the differing spectral distribution and temporal properties of the noise that they generate. In particular, the ITU-R 468 noise weighting was devised specifically for this purpose, and is widely used for professional audio and broadcast measurements. (An OSH glossary used in safety and health at work which is, adopted by ILO