Simple sleep timer for audio in Ubuntu

jonnyro@jonnyro-desktop:~$ amixer sset 'Master' mute

jonnyro@jonnyro-desktop:~$ at 2am

warning: commands will be executed using /bin/sh

at> amixer sset 'Master' mute

at>

job 1 at Wed Apr 30 02:00:00 2008

jonnyro@jonnyro-desktop:~$ ps -A | grep atd

7882 ? 00:00:00 atd