Binaural Critical Bandwidth as a Function of Signal Bandwidth

There are data in the literature which suggest that the critical band, as measured in masking experiments, may be wider for short signals than for long signals. Our data agree with this result. However, we suggest that it is the bandwidth of the signal and not only its duration that determines the critical bandwidth. Three types of signals were used: a 100-msec burst of 500-Hz sinusoid; a 100-msec burst of noise, bandpassed at 500 Hz; and a 0.1-msec click, bandpass filtered at 500 Hz. Signals were presented in both the S0N0 (signal and masker interaurally in-phase) and SπN0 (masker in-phase, signal inverted at one ear) configurations. The critical bandwidth for each signal was estimated by measuring its masked threshold in bands of noise of various widths. The important results are as follows: in S0N0 conditions the critical bandwidth for an octave-band filtered click is almost an order of magnitude larger than for a 100-msec sinusoid. Moreover, the critical bandwidth for a 100-msec octave-band filtered noise is about the same as for an octave-band click. This suggests that it is signal bandwidth that determines the width of the critical band, not its duration. In SπN0 conditions none of the above effects is observed. The critical bandwidth appears to be nearly independent of both signal duration and bandwidth.