A Swept-Sine-Type Single Measurement to Estimate Intermodulation Distortion in a Dynamic Range of Audio Signal Amplitudes

In the world of real audio systems, it is extremely important to model and identify their nonlinear behavior, especially in the case of professional audio devices. In this context, it is useful to have a quantitative estimation of the nonlinearity degree of the device, which can be obtained by exploiting an efficient and rapid measurement methodology. In this article, we propose an original estimation technique targeting the third-order intermodulation distortion (IMD) and based on a single detection. The proposed technique can be implemented both on devices operating in baseband and in bandpass. Starting from the same single detection, the technique allows to give either an estimate of the third-order IMD for the signal level actually used and to extrapolate the estimate of the IMD to signal levels different from the one actually used. Experimental verifications on real audio devices have allowed to validate the procedure in operational situations, thus confirming the validity of the proposed approach.