Editing Precedence effect (section)

== Applications ==
The precedence effect is important for hearing in enclosed spaces. With the help of this effect, it remains possible to determine the direction of a sound source (e.g. the direction of a speaker) even in the presence of wall reflections.

===Sound reinforcement systems===
Haas's findings can be applied to [[sound reinforcement system]]s and [[public address]] systems. The signal for loudspeakers placed at distant locations from a stage may be [[Delay (audio effect)#Straight delay|delayed electronically]] by an amount equal to [[speed of sound|the time sound takes to travel through the air]] from the stage to the distant location, plus about 10 to 20 milliseconds, and played at a level up to 10&nbsp;dB louder than the sound reaching this location directly from the stage. The first arrival of sound from the source on stage determines perceived localization whereas the slightly later sound from delayed loudspeakers simply increases the perceived sound level without negatively affecting localization. In this configuration, the listener will localize all sound from the direction of the direct sound, but they will benefit from the higher sound level, which has been enhanced by the loudspeakers.<ref>{{cite web|url=http://www.nti-audio.com/Portals/0/data/en/NTi-Audio-QuickGuide-FOH.pdf|title=How To Setup for a Live Sound Event|first=NTi|author-link=NTi Audio|last=Audio|website=www.nti-audio.com}}</ref>

===Ambience extraction===
The precedence effect can be employed to increase the perception of ambience during the playback of stereo recordings.<ref>{{cite journal |url=http://www.aes.org/e-lib/browse.cfm?elib=1481 |title=Extraction of Ambiance Information from Ordinary Recordings |last=Madsen |first=E. Roerbaek |journal=Journal of the Audio Engineering Society |date=October 1970 |pages=490–496 |volume=18 |number=5}}</ref> If two more speakers are placed to the left and right of the listener (in addition to the two main speakers), and are fed with the same program material but delayed by 10 to 20 milliseconds, the random-phase ambience components of the sound will become sufficiently decorrelated that they cannot be localized. This effectively extracts the recording's existing ambience, while leaving its foreground "direct" sounds still appearing to come from the front.<ref>{{cite journal|url=http://www.stereophile.com/content/extraction-ivsi-generation |title=Extraction vs Generation |journal=Stereophile |last=Katz |first=Bob |date=March 1988}}</ref><ref>{{cite book|title=Mastering Audio: The Art and the Science |last=Katz |first=Bob |year=2007 |pages=229–237 |publisher=Taylor & Francis |isbn=978-0240808376}}</ref>

=== Multichannel audio decoding ===
The effect was taken into account and exploited in the psychoacoustics of the Fosgate Tate 101A SQ decoder, developed by [[Jim Fosgate]] in consultation with [[Peter Scheiber]] and [[Martin Willcocks]], to produce much better spatiality and directionality in matrix decoding of 4-2-4 ([[Quadraphonic sound#SQ / Stereo Quadraphonic|SQ quadraphonic]]) audio.

=== Haas kicker ===
Many older LEDE ("live end, dead end") [[Recording studio|control room]] designs featured so-called "Haas kickers" – reflective panels placed at the rear to create specular reflections which were thought to provide a wider stereo listening area or raise intelligibility.<ref>Davis, Patronis "Sound System Engineering", Focal Press; 3 edition (September 20, 2006)</ref> However, what is beneficial for one type of sound is detrimental to others, so Haas kickers, like [[compression ceiling]]s, are no longer commonly found in control rooms.<ref>Philip Newell "Recording Studio Design", Focal Press; 2 edition (December 22, 2007)</ref>