Sound which is unwanted, either because of its effect on humans, its effect on fatigue or malfunction of physical equipment, or its interference with the perception or detection of other sounds.

Meaningless or erroneous bits that must be ignored or removed from a data stream, especially in communication channels.

Interfering and unwanted currents or voltages in an electrical device or system.

Nonperiodic behavior of a system that results from the presence of random driving forces, such as thermal agitation, as opposed to chaotic behavior.

Random fluctuations of electronic signals appearing in a recorded spectrum.