Appendix I
LE3000S
23
Noise-Shaping Curves
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AMP1(dBFS)
AUDIO PRECISION FFT
vs
26 JUN 94 14:42:15
NS4
NS3
NS2
FLAT
Fig. 11- 1kHz input signal -100 dB
Flat dither, with multiple noise-shapers shown
Figure 11 compares Flat dither with
NS2, NS3, and NS4 noise-shaping
curves. Note the increasing
aggressiveness of the curves, with the
pronounced dip at 4kHz and in the
12kHz region. These correspond to the
most sensitive areas of the ear to noise.
Quantization noise is shifted from these
areas to high frequencies, where the
ear is less sensitive.
Noise-shaping curves should be
selected based upon listening tests of
specific material to be dithered.
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AMP1(dBFS)
AUDIO PRECISION FFT
vs
26 JUN 94 14:37:38
NS4
NS3
NS2
HPDF
Fig. 12- 1kHz input signal -100 dB
HPDF dither, with multiple noise-shapers shown
Figure 12 compares High Pass dither
with NS2, NS3, and NS4 noise-shaping
curves. High Pass dither gives more
noise shaping in the high-frequency
band, while slightly lowering low
frequency quantization.
Note: in Figures 11 and 12, the NS1
curve has been omitted for clarity. It lies
below NS2 in both cases.
Summary of Contents for 3000S
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