Enhancing the Quality of Coded Audio Using Perceptual Criteria

Code excited linear predictive (CELP) coding standards often fail to properly represent non-speech signals because they are inherently optimized for speech. Most modern CELP coders include provisions for the inclusion of indirect perceptual criteria to counteract this problem; however no direct psychoacoustic models are employed. In this paper, we present a pre- and postprocessor for the vocoder that makes use of the MPEG-1 psychoacoustic model 1 in order to enhance the quality of the coded audio. A novel frequency-domain technique is proposed that attempts to shape the residual of a vocoder such that it falls below psychoacoustic thresholds