This study evaluated a recent proposal that the steep roll-off in fine structure–based sensitivity to interaural time delay (ITD-FS) between 1.2 and 1.5 kHz could be because of diminishing spread of excitation to a dominance region around 700 Hz. Experiment 1 measured the effects of interaurally uncorrelated masking noise lowpass filtered at 800 Hz on ITD-FS sensitivity for higher-frequency tones. Experiment 2 investigated the complementary configuration, with tones lower in frequency than the masking noise. In neither experiment was it found that masking the region around 700 Hz was especially effective in reducing ITD-FS discriminability at other frequencies.
Freyman et al. (Sun,) studied this question.