What is spatial hearing?

As with most sensory perceptions and interpretations, spatial hearing is easier to demonstrate than describe.

Spatial cues

Two important spatial cues under ideal listening conditions are: interaural time differences (ITD), resulting from the time it takes for sound to travel around the head from the nearest ear to the farthest ear and interaural level differences (ILD), resulting from the head’s ‘acoustic shadow’.

Spatial cues under ideal listening conditions

Spatial cues under ideal listening conditions generally remain constant and recur over time. Such conditions may be simulated over headphones but are otherwise difficult to acheive outside of anechoic chambers where acoustic reflections and background sounds are minimized.

Spatial cues under typical listening conditions

Spatial cues under typical listening conditions, where background sounds and acoustic reflections are prevalent, generally drift and fluctuate over time. ITD and ILD therefore rarely resemble ‘ideal’ values, except for brief moments when: 1) the amplitudes of sounds from a source substantially exceed those of background sounds, 2) past reflections have sufficiently diminished in amplitude, and 3) recent reflections have yet to arrive at the ears.

Loudspeaker driven examples

Binaural recordings

Fluctuating spatial cues and the ‘edges’ of auditory ‘images’

Methods