Noise reduction is about reducing subjective noise for the listener, not
about reducing some engineering measurement. An instrument is likely to
generate some very simple, or even pure tone, signal. With the sorts of
strategy used for noise reduction, and very aggressive settings, you
could obtain almost perfect results on such a signal, but those same
settings would make human speech completely unintelligible.
The big challenge for noise reducers is deciding what is human speech
and what is noise. That's much more difficult than identifying a pure tone.
The other sort of test signal that might be used, and the one that is
implied by the definition of noise factor, would be white noise, and
noise reducers will have no effect on the signal to noise ratio there.
They will reduce both equally.
The human brain is actually rather good at noise reduction of human
speech, but it gets tired. The aim of noise reducers is to not do quite
as well, but remove the fatigue element from the human.
As I've noted before, where the real money is in noise reduction
research is in the hearing aid industry, where the noise can be
particularly challenging, as it is generally mixed up human speech form
the other people in the restaurant.
--
David Woolley K2 06123
On 20/06/17 20:44, GRANT YOUNGMAN wrote:
You might want to look at actual (S+N)/N data. I’m not sure the visual “test”
tells the full story, since these are complex waveforms.
I did extensive measurement several years ago on the NR functions of the v1 and
v2 firmware versions of the TenTec Orion (for some reason, noise reduction not
being “magic” surfaces everywhere as a contentious issue), and the measured
data did not always match what things ”looked like”. Not saying they don’t
here, but it’s improvement in (S+N)/N that’s the end objective of NR regardless
of what the screen shot looks like.
SpectrumLab can measure this directly. http://www.qsl.net/dl4yhf/spectra1.html
On Jun 20, 2017, at 3:13 PM, wa9fvp <rep...@willcoele.com> wrote:
If you look at my data, there’s very little noise level difference in the delay
settings.
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