Earphones - no sound

[Chong Yu Meng <chongym cymulacrum net>]

Hi List!

So, I buy a pair of earphones so that I can continue watching YouTube
while my wife sleeps, and I find that when I plug them into my laptop,
the sound disappears! When I unplug it, the sound comes back on from my
laptop speakers. I looked into the Volume Control and tried twiddling
with 'alsamixer', but cannot figure out which control to set to get the
sound into my earphones. 

I'm using FC6 and running XFCE, but I'm pretty sure that the controls
are probably independent of the window manager.

Any help gratefully accepted, and thanks in advance!

pascal chong