Editing Reverberation (section)

{{Short description|Persistence of sound after it is produced}}
{{About|the acoustic phenomenon|the audio effect|Reverb effect|other uses}}
{{Redirect|Reverb}}
{{More citations needed|date=August 2021}}
{{listen|
filename=Reverberation_effect.ogg|
title=Short sample of reverberation effect|
description=Clean signal, followed by different versions of reverberation (with longer and longer decay times).
}}
[[File:C Chord With Reverb.ogg|thumb|384x384px|Reverb on a guitar]]

In [[acoustics]], '''reverberation''' (commonly shortened to '''reverb''') is a persistence of [[sound]] after it is produced.<ref>{{cite book|last=Valente|first=Michael|author2=Holly Hosford-Dunn |author3=Ross J. Roeser |title=Audiology|publisher=Thieme|date=2008|pages=425–426|isbn=978-1-58890-520-8}}</ref> It is often created when a sound is [[reflection (physics)|reflected]] on surfaces, causing multiple reflections that build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture, people, and air.<ref>{{cite book|last=Lloyd|first=Llewelyn Southworth|title=Music and Sound|publisher=Ayer Publishing|date=1970|pages=[https://www.hcmmusic.net/ 169]|isbn=978-0-8369-5188-2|url= https://www.hcmmusic.net/}}</ref> This is most noticeable when the sound source stops but the reflections continue, their [[amplitude]] decreasing, until zero is reached.

Reverberation is frequency dependent: the length of the decay, or reverberation time, receives special consideration in the architectural design of spaces which need to have specific reverberation times to achieve optimum performance for their intended activity.<ref>{{cite book|last=Roth|first=Leland M.|title=Understanding Architecture|publisher=Westview Press|date=2007|pages=104–105|isbn=978-0-8133-9045-1}}</ref> In comparison to a distinct [[echo]], that is detectable at a minimum of 50 to 100&nbsp;[[millisecond|ms]] after the previous sound, reverberation is the occurrence of reflections that arrive in a sequence of less than approximately 50 ms. As time passes, the amplitude of the reflections gradually reduces to non-noticeable levels. Reverberation is not limited to indoor spaces as it exists in forests and other outdoor environments where reflection exists.

Reverberation occurs naturally when a person sings, talks, or plays an instrument acoustically in a hall or performance space with sound-reflective surfaces.<ref>{{cite book|last1=Davis|first1=Gary|title=The sound reinforcement handbook|date=1987|publisher=Hal Leonard|location=Milwaukee, WI|isbn=9780881889000|page=259|edition=2nd|url=https://books.google.com/books?id=d7ft6F8ZUdcC&pg=PA259|access-date=February 12, 2016}}</ref> Reverberation is applied artificially by using [[reverb effect]]s, which simulate reverb through means including [[echo chamber]]s, vibrations sent through metal, and digital processing.<ref name=":0">{{Cite web|last=Weir|first=William|date=2012-06-21|title=How humans conquered echo|url=https://www.theatlantic.com/entertainment/archive/2012/06/how-humans-conquered-echo/258557/|access-date=2021-08-08|website=[[The Atlantic]]|language=en}}</ref>

Although reverberation can add naturalness to recorded sound by adding a sense of space, it can also reduce [[speech intelligibility]], especially when noise is also present. People with hearing loss, including users of [[hearing aids]], frequently report difficulty in understanding speech in reverberant, noisy situations. Reverberation is also a significant source of mistakes in automatic [[speech recognition]].

''[[Dereverberation]]'' is the process of reducing the level of reverberation in a sound or signal.