Broadened forward-masked tuning curves from intense masking tones: delay-time and probe-level manipulations

Forward-masked psychophysical tuning curves were obtained from normal-hearing listeners under two conditions: lengthened delay time between masker and probe, and increased probe level. Both conditions required higher-level masking tones and both conditions resulted in broader tuning curves. Comparisons were made of tuning curves obtained with different probe-level and delay-time combinations that were chosen to require equivalent masker levels at the probe frequency. Nearly identical tuning-curve shapes were obtained when masker level at the probe frequency was the same. The results are predicted by a two-process model, consisting of a nonlinear filter followed by an exponential decay. Tuning-curve shapes in forward masking appear to be largely dependent upon the masker level (filter output level) at which one attempts to measure them.