$ ps ax | grep esd                                     
 3710 ??  Is      0:00.53 gvim /etc/esd.conf (vim)
32588 ??  I       0:00.06 /usr/local/bin/esd -tcp -public -noterminate -nobeeps -as 2 -spawnfd 10
$ esdplay /usr/local/share/gajim/data/sounds/sent.wav  
/dev/audio: Device busy
$