The equation of mean power flow between two groups of randomly excited oscillators is derived from first principles. Subject to the coupling satisfying certain requirements, it is shown that a new parameter—the average natural frequency shift of the oscillators owing to the coupling—determines the power flow between the two groups. Power flow is directly proportional to the natural frequency shifts and to the oscillator densities (modal densities) in each group. It is suggested that this formulation has advantages over the conventional “coupling‐loss‐factor” equation of the statistical energy approach to noise‐transmission problems.