Editing Colors of noise (section)

===Pink noise===
{{Main|Pink noise}}

<!-- Image is wrong. Pink noise should fall at 10dB/dec. [[Image:Pink-noise-db-logf.png|thumb|right|Pink spectrum <br>(log frequency axis)]] -->
[[File:Pink noise spectrum.svg|thumb|right|Pink noise spectrum. Power density falls off at 10&nbsp;dB/decade (−3.01&nbsp;dB/octave).]]

The frequency spectrum of [[pink noise]] is linear in [[logarithmic scale]]; it has equal power in bands that are proportionally wide.<ref>{{cite web|url=https://www.its.bldrdoc.gov/fs-1037/dir-027/_4019.htm|url-status=dead|archive-url=https://web.archive.org/web/20210608074332/https://www.its.bldrdoc.gov/fs-1037/dir-027/_4019.htm|archive-date=8 June 2021|title=Definition: pink noise|website=its.bldrdoc.gov}}</ref> This means that pink noise would have equal power in the frequency range from 40 to 60&nbsp;Hz as in the band from 4000 to 6000&nbsp;Hz. Since humans hear in such a proportional space, where a doubling of frequency (an octave) is perceived the same regardless of actual frequency (40–60&nbsp;Hz is heard as the same interval and distance as 4000–6000&nbsp;Hz), every octave contains the same amount of energy and thus pink noise is often used as a reference signal in [[audio engineering]]. The [[spectral power density]], compared with white noise, decreases by 3.01&nbsp;[[decibel|dB]] per [[octave]] (10&nbsp;dB per [[Decade_(log_scale)|decade]]); density proportional to 1/''f''.  For this reason, pink noise is often called "1/''f'' noise".

Since there are an infinite number of logarithmic bands at both the low frequency (DC) and high frequency ends of the spectrum, any finite energy spectrum must have less energy than pink noise at both ends.  Pink noise is the only power-law spectral density that has this property: all steeper power-law spectra are finite if integrated to the high-frequency end, and all flatter power-law spectra are finite if integrated to the DC, low-frequency limit.{{citation needed|date=May 2014}}

{{Listen|filename=Pink noise.ogg|title=10 seconds of pink noise|description=}}
{{Clear}}