Haas Effect

Also called the precedence effect or principle of first arrival. If similar sounds arrive at the ear within approximately 35 ms, the sound's apparent direction is that of the direct sound. The auditory apparatus integrates delayed sounds if they fall on the ear within 20-40 ms of the direct sound. The level of the delayed components contributes to the apparent level of the sound and may be accompanied by a change in the character (timbre) of the sound.