Noise Masked Thresholds as a Function of Tonal Duration and Masking Noise Band Width

Abstract

Noise masked thresholds for 800 cps tonal pulses 25 to 400 milliseconds long were measured in masking noise bands from 18 to 1100 cps wide. It was found that the threshold remains constant for equal values of band-width pulse length product. The threshold varies according to a formula proposed on the basis of limited data in an earlier report (T. H. Schafer and C. A. Shewmaker, U. S. Navy Electronics Laboratory Report 372, 1953): S/N = m/BT0.8, where S is the signal power, N is the noise power in the pass band of the filter, B is the band width, T is the pulse length, and m is a constant.