WordNet
n. extraneous noise contaminating sound measurements that cannot be separated from the desired signal [syn: ground noise]
Wikipedia
In acoustics and specifically in acoustical engineering, background noise or ambient noise is any sound other than the sound being monitored (primary sound). Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise regulations. See noise criteria for cinema/home cinema applications.
Examples of background noises are environmental noises such as waves, traffic noise, alarms, people talking, bioacoustic noise from animals or birds and mechanical noise from devices such as refrigerators or air conditioning, power supplies or motors.
The prevention or reduction of background noise is important in the field of active noise control. It is an important consideration with the use of ultrasound (e.g. for medical diagnosis or imaging), sonar and sound reproduction.
In astronomy, background noise or cosmic background radiation is electromagnetic radiation from the sky with no discernible source.
In information architecture, irrelevant, duplicate or incorrect information may be called background noise.
In physics and telecommunication, background signal noise can be detrimental or in some cases beneficial. The study of avoiding, reducing or using signal noise is information theory.
In telephony, artificial comfort noise is used as a substitute for natural background noise, to fill in artificial silence created by discontinuous transmission systems using voice activity detection. Background noise can also affect concentration.
Usage examples of "background noise".
At first there was only a loud background noise, as of many people hurrying to and fro.
There was a garble of sound as it tried to sort signal from background noise.
Against the background noise of bubbling metal and blast beam thunder, his fall was totally silent.
His expression held mixed feelings of vexation, exasperation and perplexity: because of the high back of the booth and the background noise level created by the other patrons of the cafe, he could catch only snatches of the conversation from the next booth.
I said, having to raise my voice over the background noise in the bar.
I heard him move across a room, with a lot of music and loud talk in the background, and then the background noise cut off, as though he had stepped into another room and shut the door behind him.
Crisp commands and reports were jumbled together as a background noise.
There was a long silence that the other background noise threatened to wash into.