Interaural Time Difference

The difference in arrival time of a sound between the two ears, used by the auditory system to localize sound sources in the horizontal plane. Sound from the left reaches the left ear before the right ear; the brain uses this timing difference (up to about 0.6-0.7 milliseconds for sounds directly to one side) to determine direction. ITD is most effective for localizing low-frequency sounds (below 1500 Hz). In accessibility applications, ITD is combined with Interaural Level Difference (ILD) to create spatialized audio that conveys positional information, enabling people who are blind to perceive the horizontal location of elements in sonified images or interfaces.