Directional hearing rests on interaural time and intensity differences.

Evidence

How do we perceive the direction that a sound arrives from? The answer is that we make use of our two ears, but how? Because our two ears are separated by our head, this has an acoustic effect, which is a function of the direction of the sound. There are two effects of the separation of our ears on the sound wave: first, the sounds arrive at different times and, second, they have different intensities. These two effects are quite different, so let us consider them in turn. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 704

Categorization

• DEFINE: Introduces the two cues (time and intensity differences) underpinning binaural localization.
• XREF: Foundational to binaural beats work and the reader’s Deep Listening explorations of spatial sound perception. — connects to: Interaural level differences only emerge at frequencies above roughly 400 Hz. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1434; Interaural time and intensity cues can cancel each other in direction perception. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740; Interaural level differences grow with frequency and side placement — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1455 (+16 more)

Broader Connections

• Interaural time and intensity cues can cancel each other in direction perception. #expands (0.92) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740
• Interaural level differences and time shifts trade off to cancel each other #expands (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740
• Interaural level differences and time shifts trade off to control lateralization #expands (0.90) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1431
• Interaural time differences are computed by cross-correlating the two ear signals #expands (0.88) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1666
• Interaural level differences grow with frequency and side placement #expands (0.85) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1455
• Humans can detect interaural timing differences as small as ten to twenty microseconds #expands (0.85) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2949
• Interaural time difference ranges roughly 0-700 microseconds across azimuth #expands (0.85)
• Binaural sound localization depends on ear-level temporal and intensity encoding efficiency #corroborates (0.85) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 70
• Interaural level differences alone can shift the perceived position of a sound source #expands (0.82) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 3357
• Interaural time delays alone cannot fully determine sound source direction #qualifies (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 735
• A 5-dB hearing asymmetry doubles the perceived interaural level difference #expands (0.80) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1582
• Interaural level differences of 1-2 dB produce just-audible lateral displacement #expands (0.80) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1714
• Head size alone predicts interaural time differences well across azimuth angles #expands (0.80)
• Interaural time delay calculations must account for sound traveling around the head #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 710
• Exaggerated interaural level differences signal that a sound source is near #expands (0.78) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1529