Hierarchy of masking-level differences obtained for temporal masking

Abstract

Masked thresholds were obtained for human subjects in 4 binaural conditions (N[noise]oS[signal]o, NoSm, N.pi.So and NoS.pi.) and in 4 temporal-masking conditions (simultaneous masking, forward masking, backward masking and combined forward-backward masking). In all conditions Gaussian noise was the masker and was low-pass filtered at 5000 Hz and presented at 43-dB spectrum level. The signal was a 20-ms, 500-Hz tone gated with a 5-ms rise-decay time. The temporal interval between signal offset and masker onset (masker duration 500 ms) in the backward-masking condition was 1 ms. The temporal interval between masker offset and signal onset was 10 ms in the forward-masking condition. These same temporal intervals (but 250-ms maskers) were used in the combined foward-backward masking condition. The hierarcy of masking-level differences was the same in all of the temporal-masking procedures and matched that obtained in the simultaneous masking condition. Additional masking was obtained in the combined forward-backward masking condition for the No-So condition than for any of the binaural conditions (NoSm, N-.pi.So and NoS.pi.).