Noise shaping filter design for minimally audible signal requantization

Werner Verhelst and Dreten De Koning

To appear at Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA01), Mohonk Mountain Resort, NY, 21-24 October 2001


Signal requantization to reduce the word-length of an audio stream introduces distortions. Noise shaping can be applied in combination with a psycho-acoustic model in order to make requantization distortions minimally audible. The psycho-acoustically optimal noise shaping curve depends on the time-varying characteristics of the input signal. Therefore, the noise shaping filter coefficients are to be computed and updated on a regular basis. In this paper, we show that the optimal coefficients can be obtained by solving a simple least squares problem. Thus, an efficient scheme for minimally audible requantization can be proposed in which the noise shaping coefficients are computed from the psycho-acoustic masking curve by solving a linear matrix equation.

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