[Grml] sound appears to be muted

I can't get any sound out of my PC when booted into grml latest release candidate. I scp'ed a sound file (my dog barking) to the machine and used aplay to play it. But I didn't hear anything. Sound works when booted into linux off the hard disk.

grml@grml ~ % aplay rufus.wav Playing WAVE 'rufus.wav' : Unsigned 8 bit, Rate 22050 Hz, Mono

I also tried loading the speakup_soft module and running espeak. No error messages appear. Nothing abnormal in the syslog either. That's why I think sound is muted. What I really need is a command for unmuting a sound card. I don't know how to do that at the command line. I guess that's technically a linux question, not a grml question.