- noun normal background noise that is present all the time, usually given a reference pressure level of 0.00002 pascal in SI units
- The total noise level from all sources in a given area, either within a building or in an outside environment.
- The noise present in any given environment, especially that within which tests or observations are taking place. Such noise includes nearby and distant sources. Also called ambient noise level, background noise (1), room noise, site noise, environmental noise, or local noise.
- noun general noise which surrounds you, e.g. traffic noise, waterfalls, etc.