Precedence effect (hearing)

Article By:

Yost, William A. Parmly Hearing Institute, Loyola University, Chicago, Illinois.

Last reviewed:2001

DOI:https://doi.org/10.1036/1097-8542.YB011290

Almost all organisms live in reverberant environments in which a sound from a particular source is reflected from many surfaces (Fig. 1). Even outdoors the ground is a significant reflective surface. Thus, sounds from sources are combined with their reflections before reaching a listener's ears. Most of the time, interest focuses on the sound from the source, and not from reflective surfaces. An organism would not survive if it ran from, pursued, or tried to mate or communicate with a reflective sound instead of the sound coming from the source. Thus, from an evolutionary point of view, it is not surprising that humans are good at processing sounds in highly reflective environments. The ability to process sound from the source even when there are significant reflections is called the precedence effect. The term is derived from the observation that the sound from the source reaches a listener before that from any reflection (Fig. 1). The fact that humans process sounds from sources in reflective environments suggests that the first-arriving sound from the source takes precedence over those arriving later from reflections.

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