A scale of noise intermittancy may be represented at one extreme by a continuous noninterrupted noise and, on the other extreme, by an interrupted noise with silent intervals between successive noise bursts. The differential characteristic for various conditions along this scale is the noise level in the interval between successive noise bursts (the inter‐burst level). The effects of a wide range of periodically intermittant noise conditions upon the masked threshold of a tone and the intelligibility of speech were examined. The principal result of these tests is that the masked threshold associated with an intermittant noise can be closely described by two functions: (1) the masking produced by an interrupted noise with silent intervals between successive noise bursts, and, (2) the masking produced by a continuous uninterrupted noise at the inter‐burst level.