It is assumed that acoustic background noise is caused by a distribution of random “white” noise sources whose physical mechanism is unspecified. A law expressing the amplitude‐distance attenuation characteristic of the medium is also assumed. Several distributions of noise sources are considered: uniform volume distributions, uniform surface dipole distributions, and two mixed cases. The noise drop‐off with frequency at a point below the surface is found for each case. For an infinite volume of noise sources, this drop‐off is 6 db/octave at all frequencies. It is shown how this simple model can be generalized to other attenuation laws and other spatial and amplitude distributions of noise sources.