Editing Audio normalization (section)

==Loudness normalization==<!--[[Loudness normalization]] redirects here-->
Another type of normalization is based on a measure of loudness, wherein the gain is changed to bring the average loudness to a target level. This average may be approximate, such as a simple measurement of average power (e.g. [[root mean square|RMS]]), or more accurate, such as a measure that addresses human perception e.g. that defined by [[EBU R128]] and offered by [[ReplayGain]], [[Sound Check (iTunes feature)|Sound Check]] and [[GoldWave]]. 

For example, [[YouTube]]'s preferred loudness level is −14&nbsp;[[LKFS|LUFS]], so if an audio program is analyzed to be −10&nbsp;LUFS, YouTube will lower the loudness by 4&nbsp;dB to bring it to the preferred level. 

Loudness normalization combats varying loudness when listening to multiple songs in a sequence. Before loudness normalization, one song in a playlist might be quieter than the rest, so the listener would have to turn a volume knob up to adjust the playback volume.<ref>{{cite web |title=What are the "loudness wars" and loudness normalization? |url=https://www.hybridstudiosca.com/mastering/ |website=Hybrid Studios |access-date=1 July 2018 |archive-date=27 June 2018 |archive-url=https://web.archive.org/web/20180627230633/https://www.hybridstudiosca.com/mastering/ |url-status=dead }}</ref>

Depending on the dynamic range of the content and the target level, loudness normalization can result in peaks that exceed the recording medium's limits, causing clipping. Software offering loudness normalization typically provides the option of [[dynamic range compression]] to prevent [[clipping (audio)|clipping]] when this happens. In this situation, signal-to-noise ratio and relative dynamics are altered.

===Loudness standards===
Standardised normalized loudness levels vary by territory and application.<ref name="pro-vid">{{cite web |last1=Tépper |first1=Allan |title=How many LUFS for ideal audio loudness? Why can't we be friends? |url=https://www.provideocoalition.com/how-many-lufs-for-ideal-audio-loudness-why-cant-we-be-friends/ |website=Pro Video Coalition |date=23 March 2018 |access-date=11 July 2019}}</ref>
* −24{{nbsp}}LUFS: [[ATSC]] [https://www.atsc.org/atsc-documents/a85-techniques-for-establishing-and-maintaining-audio-loudness-for-digital-television/ A/85] (US TV), NPRSS,{{what|date=March 2022|reason=Referent of acronym is unclear}} and [[Public Radio Exchange|PRX]] radio broadcast<ref>{{cite web |url=https://help.prx.org/hc/en-us/articles/360003516334-Formatting-Audio-Files-for-Broadcast |title=Formatting Audio Files for Broadcast |website=PRX – Help Desk |publisher=[[Public Radio Exchange|PRX]] |access-date=21 March 2022 |quote=Loudness at -24 LUFS, ± 2 LU (recommended)}}</ref><ref name="pro-vid"/>
* −23{{nbsp}}LUFS: [[EBU R 128]] broadcast<ref name="pro-vid"/>
* −19 to −16 LUFS: PRX podcasts<ref>{{cite web |url=https://help.prx.org/hc/en-us/articles/360022234293-How-should-I-format-my-audio-files-for-Publish- |title=How should I format my audio files for Publish? |website=PRX – Help Desk |publisher=[[Public Radio Exchange|PRX]] |access-date=21 March 2022 |quote=Set your loudness between -16db LUFS and -19db LUFS. There is no set industry standard, [...]}}</ref>
* −14{{nbsp}}LUFS: [[Spotify]], [[YouTube]] and other [[Streaming media|streaming]] platforms<ref name="pro-vid"/>