The existing background noise level characteristic of an environment.
The level of acoustic noise existing in a room or other location, as measured with a sound level meter. It is usually measured in decibels above a reference level of 0.00002 newton per square meter in SI units, or 0.0002 dyne per square centimeter in cgs units.
The existing or inherent sound level of the area surrounding a transformer installation measured in decibels.
Ambient noise level is the level of acoustic noise existing at a given location, such as in a room, in a compartment, or at a place out of doors.
"Background" noise - from any source - that affects the listener's ability to hear what is produced by a sound system. Machinery, hum from florescent lights, traffic, et.
In atmospheric sound transmission or noise pollution, ambient noise level is the sound pressure level at a given location, normally specified as a reference level to study a new intrusive sound source. Ambient sound levels are often measured in order to map sound conditions over a spatial regime to understand their variation with locale. In this case the product of the investigation is a sound level contour map.