[alsa-devel] T410s microphone is noisy

Jens Taprogge jens.taprogge at taprogge.org
Wed Apr 21 23:23:56 CEST 2010

Hello Tobias,

On Wed, Apr 21, 2010 at 10:35:58PM +0200, Tobias Grosser wrote:
> I just tested the new v1.0.23 release including the Thinkpad T410s
> support. I works really great, however the microphone input has
> always
> a white background noise.

I am hearing some noise as well.  I will try to look into the issue when
I find the time.

> I tried an external microphone as well as the internal ones. Either the
> mixer is turned high enough that my voice can be heard good. In this
> case there is always some background noise. If I turn the mixer (or
> mic boost) down, the noise vanishes but I cannot hear myself.
> Can you give me a hint how to debug this problem?
> I already put my information here:
> http://www.alsa-project.org/db/?f=6b218b5da3fcc298e6d677a3923ec66d98f996af
> Is this some input (maybe docking station) that is not disabled? Or
> can I change some of the input amplifiers?

I do not have access to datasheets and I am not an ALSA expert either.
So I am not sure what the reason for the noise could be.  Perhaps you
could try adding mixers?  I have read somewhere that the T410s has some
sort of noise cancelation capabilities.  I do not know if they are hard-
or software based.  Perhaps you could play with the GPIOs and see if
that changes anything (e.g. enables noise cancelation).

Best Regards
Jens Taprogge

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