background noise

random signals which interfere with information transfer

In acoustics and specifically in acoustical engineering, background noise is any sound other than the sound being monitored. Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise regulations.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.
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Noun
1. extraneous noise contaminating sound measurements that cannot be separated from the desired signal
(synonym) ground noise
(hypernym) background, background signal
(hyponym) surface noise

In popular usage, environmental noise other than that from an interesting source.

The total system noise in the absence of information transmission. (188 )