[Speex-dev] Echo cancellation performance and metalic noise

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Mon Apr 10 08:17:05 PDT 2006

> I use speex1.1.10 [June 10, 2005]in my VoIP
> application and it works very good for me. But
> sometimes I get loud metalic noise. Turning off EC,
> disappears the noise right away. I use EC with
> denoiser ON, AGC OFF, echo tail 400 ms. Has anyone
> experienced this?

What happens if you turn off the denoiser?

> Since Speex1.1.11 has improvement for EC, 

Actually, 1.1.11 had a strange instability problem, so I don't recommend

> I tried with
> the latest release [Speex1.1.12, which has fixed point
> EC]. But in my test, EC performance of 1.1.12 is worse
> than Speex1.1.10. 

Could be a regression, or just the tuning that's no longer optimal for
your exact conditions.

> I can always hear some suppressed
> echo in current[1.1.12] build but with older[1.1.10]
> it is much better, almost no echo in most cases. 

Do you have any example files (that run with testecho). It's impossible
to say anything otherwise.

> I
> replaced corresponding *float* with *spx_int32_t* to
> use fixed point, in my code, to use the changed speex
> function speex_echo_cancel();
> Could that be a reason of fixed point code in Windows
> platform?

Could what be the reason for what? BTW, if you use a PC, you don't need


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