Noise (spectral phenomenon)

Noise refers to many types of random or unwanted signals, most commonly acoustic noise, but also including the following:

Acoustic noise[]

Noise in computer graphics refers to various pseudo-random functions used to create textures, including:

Gradient noise, created by interpolation of a lattice of pseudorandom gradients
- Perlin noise, a type of gradient noise developed in 1983
Simplex noise, a method for constructing an n-dimensional noise function comparable to Perlin noise
Simulation noise, a function that creates a divergence-free field
Value noise, created by interpolation of a lattice of pseudorandom values; differs from gradient noise
Wavelet noise, an alternative to Perlin noise which reduces problems of aliasing and detail loss
Worley noise, a noise function introduced by Steven Worley in 1996

Any one of many statistical types or colors of noise, such as
- White noise, which has constant power spectral density
- Gaussian noise, with a probability density function equal to that of the normal distribution
- Pink noise, with spectral density inversely proportional to frequency
- Brownian noise or "brown" noise, with spectral density inversely proportional to the square of frequency
Pseudorandom noise, in cryptography, artificial signal that can pass for random
Statistical noise, a colloquialism for recognized amounts of unexplained variation in a sample
Noise-based logic, where logic values are different stochastic processes
Noise print, a statistical signature of ambient noise, used in its suppression

Noise figure, the ratio of the output noise power to attributable thermal noise
Ambient noise level, the background sound pressure level at a given location
Noise power, with several related meanings
Noise spectral density, N_o measured in Watt/Hertz
Noise temperature, temperature that would produce equivalent semiconductor noise