Peripheral coding efficiency drives lateralization except for low-frequency ITD

Evidence

The ITD, ILD, TIME , and LEVEL tasks were intended to measure sensitivities to ITDs, ILDs, the temporal structure of the stimulus encoded by the neural phase locking, and the stimulus level, respectively. The performances of the ITD and ILD tasks were not significantly different between the age groups, while the elderly listeners exhibited significantly poorer performance in the TIME task (and in the LEVEL with a high-frequency stimulus only) than the young listeners. Significant correlations were found between thresholds for the ILD and LEVEL tasks with lowand high-frequency stimuli and for the ITD and TIME tasks for the high-frequency stimulus, implying peripheral coding efficiency as a major factor determining lateralization performance. However, we failed to find a correlation between the ITD and TIME tasks for the low-frequency stimulus, despite a large range of threshold values in the TIME task. This implies that in a low frequency region, the peripheral coding efficiency of the stimulus temporal structure is a relatively minor factor in the ITD-based lateralization performance. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1023

Categorization

• QUESTION: Why would low-frequency ITD lateralization escape the influence of peripheral temporal coding efficiency when high-frequency ITD shows it clearly? Worth chasing the mechanistic explanation in the body of the paper.