[ltp] T61 Feedback noise

[John Jason Jordan]

On Sat, 29 Dec 2007 18:37:24 +0000
Richard Neill <rn214@hermes.cam.ac.uk> dijo:

> John Jason Jordan wrote:
> > For the past week or so I have been hearing a wailing noise and I can't
> > figure out where it's coming from or what is causing it. The sound is
> > exactly like the sound a microphone makes in an auditorium when being
> > set up and the volume is too loud or some other component needs to be
> > reoriented - that is, it comes and goes and it fades in and out as I
> > move my hands around the computer. It happens only at home when the
> > computer is docked in the mini-dock, so it must have something to do
> > with the dock.

> Is the sound coming out of the speakers? (try muting them; does it go 
> away? try plugging in headphones?)
> 
> Your description could be exactly correct: the hand-waving will alter 
> standing waves. Try muting the speakers, or playing with the various 
> volume mixer options. I recommend gnome-alsamixer or alsamixergui - some 
> of the less common "knobs" may make a difference.

Muting the speakers was the first thing I tried. Also tried plugging in
headphones, but it didn't change anything. I also put my ear down to
the speakers, but that didn't work because as soon as I moved my head
the sound stopped. Ditto for putting on the headphones. 

If muting the speakers (both from the gnome panel applet and with the
mute button) did not change things, then I am assuming it's not coming
from the speakers. Also, the fact that it only happens when docked
leads me to believe that it must be coming from the dock. But the dock
has no speakers. So that means it must be something that is vibrating
the metal in the dock, turning the whole dock into a loudspeaker.

It's really weird. This is my first Thinkpad, have had it only about
three months. I was hoping someone here would say that it is a known
problem so I can stop wondering about it.