“…In birds, physiological observations are in general accordance with the Jeffress model (Jeffress, 1948): in each frequency band, binaural neurons have heterogeneous BDs, resulting from differences in axonal delays of their inputs, and the ITD of the sound source is signaled by the BD of the maximally activated neuron (Carr and Konishi, 1990). One notable disagreement is that, instead of covering the full physiological range of ITDs (Ϯ250 s in the barn owl) (von Campenhausen and Wagner, 2006), BDs rarely exceed half the characteristic period of the neuron (Wagner et al, 2007;Köppl and Carr, 2008;Carr et al, 2009), an approximate constraint called the "-limit." Figure 1A shows the BD and CF of 625 cells in the core of central nucleus of the inferior colliculus (ICCc) of the barn owl (data provided by H. Wagner (Rheinisch-Westfälische Technische Hochschule, Aachen, Germany) and previously shown in Wagner et al, 2007): high-frequency cells tend to have smaller BDs than lowfrequency cells, and 85% of all BDs fall within the -limit (i.e., BD Ͻ 1/(2CF), solid curves).…”