'METHODS AND APPARATUS FOR GENERATING COMFORT NOISE USING PARAMETRIC NOISE MODEL STATISTICS'

摘要

IN METHODS AND APPARATUS FOR CHARACTERIZING A NOISE OR INFORMATION SIGNAL AND FOR THEREAFTER USING THE CHARACTERIZATION TO RECONSTRUCT THE SIGNAL, A PARAMETRIC MODEL OF THE SIGNAL IS SUPPLEMENTTED WITH AT LEAST ONE HIGHER ORDER STATISTIC RELATING TO THE PARAMETERS OF THE MODEL. FOR EXAMPLE, IN THE CONTEXT OF DTX COMMUNICATIONS, TRANSMITTER BACKGROUND NOISE IS CHARACTERIZED BY SUCCESSIVE FRAMES OF ESTIMATED MEAN SPECTRAL MAGNITUDES, EACH FRAME BEING ACCOMPANIED BY AN ESTIMATED STANDARD DEVIATION FOR THE SPECTRAL MAGNITUDES. UPON RECONSTRUCTION, THE ESTIMATED STANDARD DEVIATION IS USED TO RANDOMIZE THE SPECTRAL MAGNITUDES AND TO THEREBY IMPROVE THE SOUND QUALITY OF THE RECONSTRUCTED NOISE. THE QUALITY OF THE RECONSTRUCTED NOISE IS FURTHER ENCHANCED BY AVERAGING, SMOOTHING OR OTHERWISE FILTERING THE MEAN SPECTRAL MAGNITUDES PRIOR TO TRANSMISSION AND/OR UPON RECEIPT.