The slow nonresonant beat disturbance (&ohgr;2−&ohgr;1, k2−k1) generated by two obliquely propagating ion acoustic waves has been observed. The beat signal wavenumber, direction, and speed agree with predicted values. The beat signal amplitude, normalized to the product of the driving wave amplitudes, exhibits a maximum when the beat signal speed is approximately equal to one‐half the ion thermal speed. The energy transfer between the two driving waves has also been observed.