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2012
Journal Article
Titel
Harmonic analysis of exponential nonlinear devices and validity of THD in judging nonlinearities
Abstract
Derivations of generalized closed-form harmonic equations for a family of polynomial-approximated and parameterized exponential nonlinear devices (NLDs) are presented. The application of this research is for nonlinear signal processing based psychoacoustic bass enhancement systems. The derived harmonic equations are used to compute THD scores analytically to show that even though the nonlinear curves are different, which may cause different perceptual effects, the THD scores turn out to be exactly the same for all six exponential NLDs. The insights gained from this mathematical analysis indicate that, even without linking to perceptual attributes such as audio quality or nonlinear distortion perception, THD is not a suitable metric to judge or measure the quantitative degrees of nonlinear curves.