On Tuesday 29 January 2008 12:58:19 pm Marzan, Richard non Unisys wrote:
> I tried googling around but no helpful content so far. I have a laptop
> with built-in sound. It uses the HDA_intel kernel module. My problem is
> that I can't silence the onboard/built-in speakers when I plug in the
> headphones to the machine. Muting sound would lead to all jacks and
> audio ports to be silenced -- not just the built-in speakers, which I
> intend to mute solely leaving sound alive on the headphone jacks. There
> are no channels readily observable to differentiate where sound goes and
> to which port with alsa-mixer. The behavior I would like to achieve is
> one that will allow me to mute onboard speakers while continuing to have
> the headphones receive audio signals. Has anyone ever done this? Any
> pointers to documentation will be appreciated.

I had an issue very similiar to this when I purchased my Acer Extensa 5620. 
After looking around for a long time I found out that the version of alsa 
that was being used in my kernel at the time didn't well support my sound 
card. I'm not sure about what alsa version is being used in the latest kernel 
now but it doesn't hurt to give it a go. Also, I had to modprobe 
snd_hda_intel with model=acer. Before inserting the module with the model 
param I was at the same exact spot you are at now. hope this helps

--
Dan Dexter