Source : Free On-Line Dictionary of Computing

noise shaping
     
         {Spectral noise} transformation in a
        quantisation processes.  Noise is "colourised" in the {time
        domain} an/or {frequency domain} by adding parts of the
        previous sample.  The {SNR bandwidth} and {SNR time integral}
        stay the same, so some noise decreases, some increases, but
        overall noise always increases.
     
        An example of noise shaping in the frequency domain is
        quantisation of samples on a {Compact Disc} to reduce noise
        below -98 dB.  The are different algorithms with slightly
        different filters, e.g. {Super Bitmapping}, {4D Recording}.
     
        A time domain example is {MPEG-4 AAC TNS}, which is a method
        to enhance quality by temporal forming of the noise in a
        transform block.
     
        (2003-07-19)