Comment 1 for bug 290691

This workaround stops it from playing any audio, including sound in flash cards:

$ SDL_AUDIODRIVER=none mnemosyne

It shows an error but runs anyway:
Unable to initialise sound.
Traceback (most recent call last):
  File "/var/lib/python-support/python2.5/mnemosyne/pyqt_ui/sound.py", line 43, in __init__
    pygame.mixer.init()
error: No available audio device