High-frequency interaural phase differences are ambiguous about azimuth location

Evidence

More specifically, there is no other location on the horizontal plane that can produce that same IPD — all other azimuthal angles will yield phase differences that are smaller than 45°. On the other hand, a 5000-Hz tone, which has a period of . ms (200 µs), will cycle about 3.15 times in 630 µs (5000 Hz * 630 * 10−6 s). Because this tone cycles many times over 630 µs, there are multiple sound source locations that result in the same IPD. For a 5000-Hz tone presented to the left ear, the IPD is equal to 1134° [(630 µs/200 µs) * 360°], but this value is equivalent to 774°, 414°, and 54°. In this case, the sound could be originating from one of four azimuthal locations. In this way, phase differences across the ears provide ambiguous information about location on the horizontal plane. As a prime example, consider that when a tone of 1587 Hz (which has a period of 630 µs) is presented to the left ear, the IPD is 0°, (630 µs/630 µs * 360° = 0°). In this case, one would not be able differentiate whether the sound is presented to the left side or to the front of the body. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1467

Categorization

Category: Causal Relationships

• QUESTION: Is this ambiguity the reason localization of high tones relies on level not phase?

Related

• High-frequency tones produce ambiguous azimuthal localization due to phase wrapping. (similarity 0.90)
• High-frequency tones yield multiple possible source locations from a single phase difference (similarity 0.90)
• Phase delays beyond 180 degrees make direction judgments ambiguous (similarity 0.87)
• Phase-based sound localization becomes ambiguous beyond 180 degrees phase shift (similarity 0.87)
• Panning between two speakers recreates a phantom source positioned by interaural phase shift (similarity 0.83)
• Ear offset from the head’s center makes arrival time shift with source azimuth (similarity 0.82)
• Interaural level differences only emerge at frequencies above roughly 400 Hz. (similarity 0.81)
• The ear is far less sensitive to phase than to amplitude of frequency components (similarity 0.80)
• The ear resolves low-frequency direction by measuring phase shift (similarity 0.80)
• The superior olivary complex sharpens phase locking to enable left-right sound localization (similarity 0.80)
• Phase-based localization sensing has a hard frequency ceiling near 1.6 kHz (similarity 0.80)
• Phase-based directional hearing works only below about 743 hertz (similarity 0.80)
• The ear lacks the eye’s directional receptors, relying on canal analysis (similarity 0.79)
• Toe-in aimed at the listener compensates off-center phantom drift only at mid-to-high frequencies (similarity 0.79)
• The ear cannot sense a tone’s absolute phase but does sense phase differences. (similarity 0.79)

Broader Connections

• Panning between two speakers recreates a phantom source positioned by interaural phase shift #expands (0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2200