Backward Masking for Tones in Narrow-Band Noise

Abstract

Appropriate transformations based on the theory of temporal summation were used to determine backward masking as a function of the time interval between the onset of 800-, 1000-, 1200-, and 1750-cps tones and the onset of an 80-dB narrow-band noise centered at 1000 cps, which partially masked the tones. Backward masking was found to consist of at least two phases separated by a transition region in which threshold did not appear to be determined by the duration of the probe tone. Masking at 800, 1200, and 1750 cps was found similar to that at 1000 cps, but did not extend as far back in time. The results are interpreted to mean that masking occurs first for those tones within a noise band and then spreads to those frequencies outside the band until the pattern commonly observed under simultaneous masking is obtained. [Research supported by a contract between the U. S. Office of Naval Research NOnr 669(13) and Syracuse University.]