Masked discrimination of interaural time delays with narrow-band signal

Interaural time just-noticeable-difference (jnd) of a narrow-band noise masked by a wideband noise was measured for nine different interaural configurations of the masking noise at a fixed signal-to-noise ratio. The narrow-band noise was 1/3 octave wide centered about 500 Hz, and the wideband masker was bandpass filtered between 250 and 1500 Hz. Our results are in agreement with earlier results with tones [M. F. Cohen, J. Acoust. Soc. Am. Suppl. 1 64, S35 (1978); J. Acoust. Soc. Am. 70, 1289-1293 (1981); J. E. Slocum and R. M. Stern, J. Acoust. Soc. Am. Suppl. 1 68, S60 (1980)] and are the opposite of what may be expected from the results of binaural detection experiments: the jnd is largest for the interaurally phase reversed masker and smallest for the diotic masker. In addition, no consistent relation was observed between the size of the jnd and the perceptual location of the masker. Predicted jnds were calculated from a model based on the interaural phase difference of the stimuli in the two ears and were in rough agreement with the experimental results.