Phenomenon of human hearing where by the ears are able to localize sounds (determine where they came from) by the difference in time from when the sound first enters one ear to when it enters the other ear. As long as the sound is heard in the second ear within 35 milliseconds, the brain does not distinguish between the sound as coming from two sources even if the loudness of the sound is different for each ear (if the sound arrives in the second ear after 35 milliseconds it is distinguished as a separate and discrete sound). Instead, the brain realizes it is the same sound arriving later to the second ear and uses that information to locate the sound’s origin. When the sound reaches the second ear, it is not sensed as a different sound but as part of the original delayed in its transmission. hen a sound reaches both ears at the same time, it is located as directly ahead. When a sound enters the right ear and then shortly thereafter the left ear, the sound is localized to the right and its specific position is determined by the total difference in time between its stimulation of the second ear. The precedence effect (also known as the Haas Effect) enables people to recreate a dimensional sound field from two sound sources thus allowing the use of stereo to recreate an acoustic space.