Noise (nonfiction)

Noise has several usages.

Noise is unwanted sound judged to be unpleasant, loud or disruptive to hearing. From a physics standpoint, noise is indistinguishable from sound, as both are vibrations through a medium, such as air or water. The difference arises when the brain receives and perceives a sound.

In experimental sciences, noise can refer to any random fluctuations of data that hinders perception of an expected signal.

In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. Thermal noise is unavoidable at non-zero temperature (see fluctuation-dissipation theorem), while other types depend mostly on device type (such as shot noise, which needs a steep potential barrier) or manufacturing quality and semiconductor defects, such as conductance fluctuations, including 1/f noise.

In communication systems, noise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources.

Noise is typically distinguished from interference, for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measures.

Noise is also typically distinguished from distortion, which is an unwanted systematic alteration of the signal waveform by the communication equipment, for example in the signal-to-noise and distortion ratio (SINAD) and total harmonic distortion plus noise (THD+N).

While noise is generally unwanted, it can serve a useful purpose in some applications, such as random number generation or dither.

A noise trader is a stock trader whose decisions to buy, sell, or hold are irrational and erratic.

Fiction cross-reference

• Noise trader

Nonfiction cross-reference

• Noise trader (nonfiction)
• Signal (nonfiction)

External links:

• Noise @ Wikipedia
• Noise (electronics) @ Wikipedia