<communications> 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.
