Spatial Hearing Mechanisms and Sound Reproduction

1. The time of arrival of the wave front of a sound event at the ears, or more specifically, the difference in arrival times at the two different ears. A sound source anywhere on a line from due front, through due above to due back (the median plane) will have its wave front arrive at the two ears simultaneously. Move the source away from this line and one ear will begin to receive the wave front before the other. This is known as the Interaural Time Delay or ITD. This effect is only usable up to a frequency where the wavelength of the sound approaches twice the distance between the ears. Over that, it provides only ambiguous cues.