2d user added, no sound

[Guillaume Duveau]

Hello,

I've added a second user, but I when I log into this user, I have the 
message : "No volume control elements and/or devices found."

OK, I did :
sudo adduser [my2duser] audio

OK for this message ; but still no sound. When the gnome session opens, 
no sound. When I try to play an Ogg with Rythmbox I get : "Could not 
open resource for writing".

Can you help me ?