[speex-dev] More Speex (pre-processing) Options

Tom Grandgent tgrand at canvaslink.com
Wed Nov 26 14:50:03 PST 2003

These are my results with the Speex AGC and denoiser:

Over the past couple of months, I've spent probably 10-20 hours of 
conversation with Speex (wideband) doing AGC + denoiser on both ends 
of the call.  I think it does an excellent job of removing most noise 
while keeping speech intact.  Yes, it's possible to make some constant 
noise (like humming) and have that get removed, but I've *never* had 
that be a problem in real conversation.

The only thing that's slightly annoying is that the person I usually 
converse with has some fairly constant low-frequency noise, and this 
noise is somewhat noticible while the person is talking.  If I try to 
mask it out using an FFT-based high-pass filter before encoding with 
Speex, I get some annoying and strange sounds during periods of 
silence.  I'm guessing the AGC is picking up on some kind of residue 
from my filtering process.

Finally, every now and then I hear some musical artifacting with 
Speex's AGC + denoiser, but it's not very troublesome at all.

To conclude: I'm really happy with the AGC + denoiser.  Adjusting 
the mic volume level is no longer necessary, and having the denoiser 
automatically adapt to changing noise conditions is valuable.  If 
echo cancellation worked, that would be the icing on the cake.


<p>Tom Harper (harper at archila.com) wrote:
> Hi,
> So far there does seem to be an improvement in open air mike noise vs.
> no denoising, especially in terms of handling feedback- but that is just on
> my laptop, which is far quieter than a desktop sound card might be- As far
> as removing it completely, I think there were a few posts about that a couple
> of months ago that suggested some good approaches- of course, the best
> way to solve it is to get a good head phone/directional mic setup :)
> Tom
> At 10:52 AM 11/26/2003, Tongbiao Li wrote:
> >This is only remotely related: just out of curiosity, does
> >speex_preprocess work very well for you ?
> >
> >It only works to certain extend for me, and does not seem to completely
> >remove noise from sound card.  Even if you unplug the microphone, it
> >still could not get rid of the noise.
> >
> >Any idea how it could be totally eliminated ?
> >
> >
> >Thanks

--- >8 ----
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