Temporal Effects in Simultaneous Masking by White-Noise Bursts

Abstract

The motivation of the research described was to investigate the behavior of a masking transient that indicates that masking of a short signal pulse by a longer white-noise burst is stronger at the beginning of the masker burst than later. The threshold of signal pulses masked by masker bursts was measured as a function of different variables such as bandwidth and center frequency of the signal, delay between onset of masker and onset of signal, duration of signal and masker, level of masker, and repetition rate. The results reveal very little “overshoot” of the threshold of short pulses as a function of the ON time of the masker if the signal and the masker have the same or similar broad spectra. The overshoot increases up to 13 dB as the bandwidth of the signal decreases down to that of a tone. The size of the “overshoot” and the prior excitation seem to be related to each other. Taking this in account, the thresholds under different conditions can be calculated on the basis of detection models. The measured and the calculated values are in good agreement.