Intermodulation distortion  --  A constituent of non-linearity distortion consisting of the occurrence, in the response to co-existent sinusoidal excitations, of sinusoidal components (intermodulation products) whose frequencies are sums or differences of the excitation frequencies or of integral multiples of these frequencies. Intermodulation distortion manifests as a type of amplitude change in which sum and difference tones (harmonics of the original signal) are present in the recorded signal.