Measurements were made of the masking of pure tones by bands of noise, the width of each band corresponding to a pitch interval of 250 mels, with band level varied from 40 to 120 db SPL. The masked audiograms were compared to the frequency characteristics of the bands of noise. It was found that published values for the critical bands predict the masking for tone within the band. More masking than would be predicted is found for the frequencies above a band. Below the band, the masked threshold is again predicted precisely by the critical‐band hypothesis, but only to a point beyond which, for high noise levels, a “remote” masking, which is constant as a function of frequency for any particular level, is observed and is much more than can be predicted from the effective levels (from either system noise or imperfect filtering) obtaining at those low frequencies where this masking is observed. Whereas for tone within the band masking increases linearly with level, this “remote” masking rises in an accelerated manner with level and then decelerates at the highest levels. Some speculative interpretation is attempted. [This work was supported under Contract No. AF 18(600)‐131 with the U. S. Air Force.]