• As a relation between the degree

• As a relation between the degree of the nonlinearity(third, fifth, etc.) and the frequency of the side tone(such as IM3, IM5, etc.), can be mentioned that the IM5 tones are not affected by third-degree nonlinearities. but IM3 tones are functions of both third- and fifth-degree(and higher) nonlinearities. That means at low signal amplitudes, where the fifth-order distortion products can be neglected, the amplitudes of the IM3 tones are proportional to the third power of the input amplitude.