Ok, I found what was wrong after messing in .purple/prefs.xml
<pref name='sound'> <pref name='while_status' type='int' value='1'/> </pref>
The default value of 1 works. Changing this to
<pref name='sound'> <pref name='while_status' type='int' value='3'/> </pref>
will make the program die on message reception.
Ok, I found what was wrong after messing in .purple/prefs.xml
<pref name='sound'>
<pref name='while_status' type='int' value='1'/>
</pref>
The default value of 1 works. Changing this to
<pref name='sound'>
<pref name='while_status' type='int' value='3'/>
</pref>
will make the program die on message reception.