Psychoacoustic bass audio signal enhancement can be accomplished using a monotonic, asymmetric polynomial distortion. A non-linear process applies a monotonic, asymmetric polynomial distortion function that has continuous first and second derivatives to generate even and odd harmonics of missing fundamental frequencies. This polynomial distortion produces the desired psychoacoustic effect with a fairly rapid roll-off so as to avoid unpleasant aliasing. Moreover, the lack of first-order discontinuities prevents clicks or glitches.