A general principle of linear systems that when applied to wave phenomena asserts that the combined effect of any number of interacting waves at a point may be obtained by the algebraic summation of the amplitudes of all the waves at the point. For example, the superposition of two oscillations x1 and x2, both of frequency ν, produces a disturbance of the same frequency. The amplitude and phase angle of the resulting disturbance are functions of the component amplitudes and phases. Thus, if
and
the resultant disturbance, x, will be given by:
where amplitude A and phase angle Δ are both functions of a1, a2, δ1, and δ2.