[Speex-dev] Noise suppression less than AGC gain

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Tue May 29 06:03:28 PDT 2007

> I've had a small case with noise suppression and AGC. I have a fairly
> noisy environment here, and with the default parameters, noise
> suppression works fairly well while I talk. However, when I shut up, AGC
> starts slowly increasing the gain until it has amplified whatever noise
> is left to levels about equal to having no filtering at all. As soon as
> I talk, AGC backs down fairly quick and the noise is again gone.

Are you using 1.2beta2? There's been lots of changes in both noise
suppression and AGC since 1.2beta1. So make sure you use 1.2beta2 if
that's not already the case.

> Decreasing the AGC max gain and increasing the ammount of noise
> suppression fixed things, but it might be an idea to change the defaults
> slightly?

It's actually possible to make noise suppression more aggressive, with a
price in quality. But in the end, it's mainly a matter of making sure
the AGC does the right thing. After you speak, does the level of the
noise start going up again?


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