Cross-correlation sidelobes near 1 kHz stem from interaural phase ambiguities

Evidence

Near 1 kHz, sidelobes are seen in the functions, which occur because the period of the centre frequency of auditory bands is shorter than 1 ms, and the IACC analysis also finds high correlation in the signals when the time lags equal the delay or the phase advances by 2π. … At higher frequencies, the IACC no longer shows side bands, since the temporal details of the signals are mostly lost, which is also evident in Figure 13.12c. Instead, only the temporal envelope is preserved, and since, in this case, the signal was a short excerpt of the vowel /a/, a rather strong temporal structure remains. The cross-correlation between the left and right signals then results in only a single hump in the IACC functions. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1671

Categorization

• XREF: Phase ambiguity causing spatial localization errors near 1 kHz connects to the classic ‘cone of confusion’ and why low-frequency ITD cues break down — relevant to HRTF-based audio rendering.
• QUESTION: The 2π phase-advance sidelobe phenomenon may explain why some listeners localize better than others near 1 kHz — worth checking whether there are individual differences in detecting these ambiguous lags.