Spike-Timing-Based Computation in Sound Localization
Figure 14
Distribution of interaural phase differences (IPD) in the binaural signals and preferred IPDs of binaural neurons.
The color codes follow the conventions of Fig. 3 of Harper and McAlpine (2004). (A) Distribution of IPDs across all HRTFs (including all measured azimuths and elevations), as a function of frequency. The dark triangle corresponds to the physical limit of ITDs, which is smaller than half a period for low frequencies, while the light triangle corresponds to the situation when the maximum ITD is between π and 2π, which makes larger IPDs more represented than smaller ones (imagine folding a larger triangle at the vertical lines IPD = −π and IPD = π). (B) Distribution of best IPDs of neurons in the approximate model as a function of their preferred frequency. Best IPDs were measured using delayed white noise. The horizontal line at 400 Hz represents the frequency above which best delays should be continuously distributed, according to Harper and McAlpine (2004). A very similar distribution was obtained with the ideal model (not shown).