ITD spans 0-700 microseconds across azimuth independent of frequency

Evidence

The ITD varies from 0 μs to approximately 600–700 μs when the azimuth angle varies from 0◦to 90◦. The values derived by the spherical model match the measurements from real heads well, as shown in the figure. Figure 12.10a shows the dependency of the ITD on frequency and on direction as a surface. The values are computed using a cross-correlation type of binaural auditory model. The ITD does not depend significantly on frequency. Only at low frequencies below about 700 Hz are the maxima of the ITDs a bit higher. Some irregularities in ITD functions at frequencies above 2 kHz also exist, and these are due to the complex multi-path wave propagation on the contralateral side. The coherence of the binaural signals is typically lower there, which causes the irregularities in cross-correlation computation. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1429

Categorization

• QUESTION: The spherical-head model accuracy claim and its frequency independence are useful quantitative facts for any audio engineering application, potentially worth cross-checking exact 600 vs 700 microsecond figures.
• XREF: connects to: Interaural time difference ranges roughly 0-700 microseconds across azimuth; Estimated ITDs match theoretical values especially at low frequencies — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1667

Broader Connections

• Interaural time difference ranges roughly 0-700 microseconds across azimuth #corroborates (1.00)
• Estimated ITDs match theoretical values especially at low frequencies #corroborates (0.75) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1667