White noise

White noise is a noise that is described by a constant power spectral density in a particular frequency range. In psychoacoustics white noise is perceived as a strong height fitting noise. White, in the bandwidth limited noise is often used in engineering and natural sciences to reflect disturbances in an otherwise ideal model, such as to describe random noise in a transmission channel.

The term for the color white is in a figurative sense, to understand, to white light in which different optical frequency components are superimposed to a white color impression. However, subjectively perceived by humans has white light on no constant power density spectrum.

Description

Characteristic of White noise is a constant power density spectrum:

In the unlimited bandwidth white noise is to be understood as a limiting case of model, which has an infinitely high performance, and therefore does not occur in practice. In real systems, white noise always occurs only in a constant in this range Frequenzebereich power density spectrum. The power density spectrum outside this range falls upwards, at sufficiently high frequencies only, always approaches 0 from.

Is the autocorrelation function of white noise is a Dirac pulse at the point zero. That is, the noise at a particular time is uncorrelated to all other times. The term white noise is also used for discrete-time signals are used whose individual samples are uncorrelated.

White noise can occur in different probability distributions. A normal distribution is the normal distribution or Gauss distribution, which serves as part of the signal processing for describing the disturbance of the transmission channels. For these channels, the noise is additive disturbance as with introduced and then referred to as additive white Gaussian noise. Also thermal noise on electrical resistors can be primarily described by white Gaussian noise. White noise can in principle but also occur in other distributions.

Applications

In psychoacoustics white noise is used as a method to combat noise and in the field of tinnitus retraining therapy as Masker - noise or other noise is subjectively less noisy and bothersome if you overlaid it white noise. Noise, all frequency components listen to where as roughly identical, is called 1/f-noise. This indicates a decrease in the frequency block density spectrum.

In the stochastic white noise, the name refers to a discrete stochastic process of uncorrelated random variables with mean 0 and constant variance. It is weakly stationary. The white noise is the simplest stochastic process, however, many complex processes and time series are constructed from these, such as the random walk or ARMA processes.