[Fr. noise, strife, brawl]

1. Sound of any sort, including that which is loud, harsh, confused, or senseless. SEE TABLE: Typical Noise Levels in Decibels and Their Effect; SEE: acoustic trauma; SEE: pollution, noise
2. In electronics or physics, any electronic disturbance that interferes with the signal being recorded or monitored. In electrocardiography, the 60-cycle alternating current used to power the machine may be inadvertently recorded. This obscures the signal from the electrical activity of the heart.
3. Unwanted information on a radiograph caused by fogging or scattered radiation.
Typical Noise Levels in Decibels and Their Effect

SituationLevel (decibels)Effect
Jet engine (close by)*140Harmful to hearing
Jet takeoff*130
Propeller aircraft*120
Live rock band110Risk of hearing loss
Heavy-duty truck90
Private car; business office70Probably no risk of permanent damage to hearing
Wooded residential area50No harm
Rustle of leaf10

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