Selectivity and representation of interaural level differences (ILD) across carrier waveforms
Whereas neural responses are cyclic as ITD is varied, neural responses as ILD is varied are thought to be sigmoidal.
Contributions to neural representations of auditory space from ILD may be modeled similarly to how contributions from ITD were modeled. Two important differences being:
(1) activities evoked by peripheral ILDs do not become spatially ambiguous and
(2) activities in the left and right hemispheres generally indicate a single direction, even under conditions when ILD fluctuates widely over time.
ILD-evoked activities are best considered together with ITD-evoked activities and vice versa.
Looking ahead, combined activity patterns may be ‘shifted’ or ‘pulled’ when ILD-evoked activities are combined with ITD-evoked activities over time. Thus, ILD-evoked activities in neurons with ‘labels’ that are to the left of those in neurons responsive to ITD may act to shift/pull the combined activity pattern to the left.
ITD-evoked activity sub-maxima or ‘edges’ that exceed the so-called ‘π-limit’ may also be shifted/pulled toward the midline and away from the ‘π-limit’.
Because ILD-evoked activities are not subject to phase wrapping, phase-ambiguous activities evoked by peripheral ITDs may also be diminished.