Editing Precedence effect (section)

{{Short description|Psychoacoustical phenomenon}}
{{redirect-distinguish|Haas effect|de Haas–van Alphen effect|Einstein–de Haas effect|Shubnikov–de Haas effect}}

The '''precedence effect''' or '''law of the first wavefront''' is a [[Sound localization|binaural]] [[psychoacoustics|psychoacoustical]] effect concerning [[Reflection_(physics)#Sound reflection|sound reflection]] and the [[perception]] of [[Echo (phenomenon)|echoes]]. When two versions of the same sound presented are separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single auditory event; its perceived spatial location is dominated by the location of the first-arriving sound (the first [[wave front]]). The lagging sound does also affect the perceived location; however, its effect is mostly suppressed by the first-arriving sound.

The '''Haas effect''' was described in 1949 by '''Helmut Haas''' in his Ph.D. thesis.<ref>{{cite web |url=http://www.aes.org/par/h/#Haas_Effect |title=Pro Audio Reference  |quote=After Helmut Haas's doctorate dissertation presented to the University of Gottingen, Gottingen, Germany as "Über den Einfluss eines Einfachechos auf die Hörsamkeit von Sprache;" translated into English by Dr. Ing. K.P.R. Ehrenberg, Building Research Station, Watford, Herts., England Library Communication no. 363, December, 1949; reproduced in the United States as "The Influence of a Single Echo on the Audibility of Speech," J. Audio Eng. Soc., Vol. 20 (Mar. 1972), pp. 145-159. |access-date=2020-04-18}}</ref> The term "Haas effect" is often loosely taken to include the precedence effect which underlies it.