White noise Guide, Meaning , Facts, Information and Description
This article is about white noise as a scientific concept, see also:- White Noise as a 1985 novel by Don DeLillo.
- White Noise (movie) as a 2004 movie by Geoffrey Sax.
White noise is a signal (or process) with a flat frequency spectrum. In other words, the signal has equal power in any band, at any centre frequency, having a given bandwidth.
An infinite-bandwidth white noise signal is purely a theoretical construct. By having power at all frequencies, the total power of such a signal would be infinite. In practice a signal can be "white" with a flat spectrum over a defined frequency band.
| Table of contents |
|
2 Pink noise 3 Applications 4 Whitening a signal 5 See also 6 External links |
A signal that is "white" in the frequency domain must have certain important statistical properties in time. For example, it must have zero autocorrelation with itself over time, except at zero timeshift. Conversely, if the autocorrelation of a signal has those properties (zero except at zero timeshift), the signal is white.
Being uncorrelated in time does not however restrict the values a signal can take. Any distribution of values is possible (although it must have zero DC component). For example, a binary signal which can only take on the values +1 or -1 will be white if the sequence of zeros and ones is statistically uncorrelated. Noise having a continuous distribution, such as a normal distribution, can of course be white.
It is often incorrectly assumed that Gaussian noise (see normal distribution) is necessarily white noise. However, neither property implies the other. Thus, the two words "Gaussian" and "white" are often both specified in mathematical models of systems. Gaussian white noise is a good approximation of many real-world situations and generates mathematically tractable models.
A closely related concept is pink noise. Its frequency spectrum is not flat, but has equal power in octave bands. Pink noise is perceptually white. That is, the human auditory system perceives equal magnitude on all frequencies.
One use for white noise is in the field of architectural acoustics. Here in order to submerge distracting, undesirable noises (for example conversations, etc.,) in interior spaces, a constant low level of noise is generated and provided as a background sound.
White noise has also been used in electronic music, where is it used either directly or as an input for a filter to create other types of noise signal.
In statistics, a random vector is said to be "white" if its elements are uncorrelated and have unit variance. This corresponds to a flat power spectrum.
A vector can be whitened to remove nonzero correlations. This is useful in various procedures such as data compression.
One common method for whitening a signal is to perform the following calculation:
This is an Article on White noise. Page Contains Information, Facts Details or Explanation Guide About White noise Statistical properties
Pink noise
Applications
Whitening a signal
where:
is the matrix to be whitened,
is the orthogonal matrix of eigenvectors of
is the diagonal matrix of corresponding eigenvalues and =
See also
External links