Editing Colors of noise (section)

===White noise===
{{Main|White noise}}

[[Image:White noise spectrum.svg|thumb|right|White noise has a flat power spectrum.]]

[[White noise]] is a [[Signal (electrical engineering)|signal]] (or process), named by analogy to [[Electromagnetic spectrum#Visible radiation (light)|white light]], with a flat [[frequency spectrum]] when plotted as a linear function of frequency (e.g., in Hz). In other words, the signal has equal [[power (physics)|power]] in any band of a given [[Bandwidth (signal processing)|bandwidth]] ([[power spectral density]]) when the bandwidth is measured in [[hertz|Hz]].  For example, with a white noise audio signal, the range of frequencies between 40 [[hertz|Hz]] and 60&nbsp;Hz contains the same amount of sound power as the range between 400&nbsp;Hz and 420&nbsp;Hz, since both intervals are 20&nbsp;Hz wide. Note that spectra are often plotted with a logarithmic frequency axis rather than a linear one, in which case equal physical widths on the printed or displayed plot do not all have the same bandwidth, with the same physical width covering more Hz at higher frequencies than at lower frequencies. In this case a white noise spectrum that is equally sampled in the logarithm of frequency (i.e., equally sampled on the X axis) will slope upwards at higher frequencies rather than being flat. However it is not unusual in practice for spectra to be calculated using linearly-spaced frequency samples but plotted on a logarithmic frequency axis, potentially leading to misunderstandings and confusion if the distinction between equally spaced linear frequency samples and equally spaced logarithmic frequency samples is not kept in mind.<ref name="Peters-2012">{{cite web|url=https://physics.mercer.edu/hpage/psd-tutorial/psd.html|author=Randall D. Peters|date=2 January 2012|title=Tutorial on Power Spectral Density Calculations for Mechanical Oscillators}}</ref>

{{Listen|filename=White noise.ogg|title=10 seconds of white noise|description=}}
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