Frequency-Domain Algorithms for Audio Signal Enhancement Based on Transient Modification

Two processing approaches that enable perceptually compelling modification of audio signals via accentuation or suppression of transients are described. The first algorithm uses a frequency-domain analysis and a soft-decision paradigm to characterize transients in the signal; the transient characterization is then used to drive a nonlinear frequency-domain modification. In the second algorithm the modulation spectrum of the audio signal is manipulated by modifying the time trajectories of spectral envelopes in different frequency bands; scaling of higher modulation frequencies with shelving filters is used to modify rapidly changing signal events, thus altering transient components without the need for explicit detection. The algorithms are described in detail and it is demonstrated that they can achieve substantial modification of a signal's perceptual attributes without introducing significant artifacts.