The Precedence Effect

Two identical sounds played in close succession will be heard as a single fused sound.

• 1 ms $<$ lag $<$ 5 ms: effect heard with clicks;
• lag $<$ 40 ms: heard with more complex sound;
• lag $>$ 40 ms: second sound is heard as an echo

Precedence Effect: the perceived location of successive sounds heard as fused but coming from different locations, is dominated by the location of the sound that first reaches the ears (first-arriving wavefront).

• in a room with reflecting surfaces, a combination of many reflected sounds may reach our ear with greater intensity than direct sound;
• the tendency is to hear the sound as coming from the direction from which it first reaches the ears.

Experiment: Play voice from two speakers: from where do you hear the voice? precedence.pd

It is common to place an amplification system behind the speaker so that the sound is perceived as coming from the speaker.