This paper describes a new approach to improving the coding of harmonic signals in transform-based audio codecs employing pulse vector quantization. The problem occurs when coding at low rate signals with varying levels of harmonics. As a result of vector quantization (VQ), some lower level harmonics may be missed or fluctuating and cause perceptual artifacts. The proposed solution consists of applying perceptual weighting to the computed synthesis error in the search loop of the VQ. The objective being to de-emphasize the error in the high tonal peaks where signal energy partially masks the quantization noise. Simulation results over mixed musical content showed a noticeable improvement in perceptual scores, particularly for highly harmonic signals.
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