the haas effect

The last phenomenon we are going to describe is the Haas effect, that is related to sound localisation:

If two sounds of equal frequency content and intensity are played from different directions, we will only hear the first one to arrive, and we will perceive only one sound coming from that direction.

Within some limitations in the difference of arrival time and in the intensity, the second sound may also be a little louder than the first, but we will still perceive just one sound. The Haas effect is used in concert sound systems, so that multiple speakers do not affect the perceived direction of the sound coming from stage, and in surround sound technologies.