Discrimination of interaural delays in complex waveforms: Spectral effects

Sensitivity to interaural delays in high‐frequency waveforms was examined using amplitude‐modulated signals. Carrier frequencies ranged from 2 to 6 kHz, and modulation was varied from 50 to 550 Hz. The signals’ components were not harmonically related. Findings include: (a) As carriers exceed 3 kHz, a broad region appears (from 150 to 350 Hz of modulation) over which there is little change in sensitivity to interaural time differences in the modulation envelope. (b) Signals with interaurally‐discrepant carriers are more difficult to lateralize, but for carriers at and above 4 kHz, a region of constant performance can also be found as the interaural frequency difference is increased from zero. (c) Variations in modulation depth are useful in approximating the sideband attenuation that may occur as wideband signals are filtered by the auditory system. Such a technique allows an assessment of the importance of critical bands in these phenomena.