Noise

Any unwanted sound that interferes with speech and hearing, causes damage to hearing, or annoys a person.

In the most general terms, noise is the undesired part of the process being observed or measured. Its complement, the desired part, is usually referred to as the signal.

Unwanted components in a signal that degrade the quality of data or interfere with the desired signals processed by a system.

An undesired disturbance within the frequency band of interest; the summation of unwanted or disturbing energy introduced into a communications system from man-made and natural sources. 2. A disturbance that affects a signal and that may distort the information carried by the signal. 3. Random variations of one or more characteristics of any entity such as voltage, current, or data. 4. A random signal of known statistical properties of amplitude, distribution, and spectral density. 5. Loosely, any disturbance tending to interfere with the normal operation of a device or system.