Additivity of Forward and Backward Tonal Masking

The temporal masking of a 1000‐Hz probe tone by a 70‐dB‐SPL 1000‐Hz masker was investigated using a forward masking paradigm, a backward masking paradigm and a combined forward‐backward masking piradigm. The duration of the probe tone was 10 msec with a 4‐msec rise‐fall time, while the masker duration was 60 msec with a 4‐msec rise‐fall time. In the forward and backward masking conditions, the masking of the probe tone was measured as a function of the time (ΔT) between the masker and the probe tone. Selected ΔT's from 0 to 20 msec were used. In the combined forward‐backward masking conditions, masking was measured as a function of both the inter‐masker‐interval and the position of the probe in time with respect to the forward and backward maskers. Inter‐masker‐intervals ranged from 10 to SO msec. Observers' thresholds were measured using a 2ATFC procedure. Combined forward‐backward masking conditions produced masking levels which were higher than expected on the basis of a residual power prediction. The ...