Sound localization

Sound localization is the ability to infer a sound source’s direction and distance from acoustic cues. It relies chiefly on differences between the signals reaching the two ears and on changes in sound caused by the head and outer ears.

Interaural time difference: The difference in arrival time of a sound at the two ears. For low-frequency sounds, this timing disparity is a major cue to left–right direction.
Binaural hearing: Hearing with two ears and combining their signals to perceive sound. Sound localization uses comparisons between the signals arriving at both ears.
Binaural recording: A recording method that captures sound with two channels arranged to reproduce human-like spatial hearing. It preserves directional cues that can make reproduced sources seem spatially located.
Monaural hearing: Hearing with one ear or processing sound without comparing signals from two ears. It removes interaural comparisons, leaving spectral and environmental cues to guide direction judgments.
Interaural level difference: The difference in sound level reaching the two ears, largely caused by the head blocking sound. The head’s acoustic shadow makes this level disparity especially useful for locating high-frequency sounds.
Auditory system: The organs and neural pathways that detect and process sound. Its peripheral and central structures transform acoustic cues into spatial judgments.
Virtual auditory display: A system that uses sound to present spatial information or create perceived sound sources in virtual space. It applies localization cues to place synthetic sounds around a listener.
Front–back confusion: An error in which a sound source in front is perceived as behind, or vice versa. Similar binaural disparities can make front and rear sources difficult to distinguish.
Head-related transfer function: A description of how the head, torso, and outer ears filter sound from a particular direction before it reaches the eardrum. Direction-dependent filtering supplies spectral cues that distinguish elevations and front from back.
Pinna: The visible outer portion of the ear that funnels sound into the ear canal. Its folds create direction-dependent spectral changes used to estimate elevation.

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