Comment 4 for bug 390318

I found that the combination of OSS and ICH did the trick.

ALSA gave me lots of output glitches, as cited above.
PulseAudio provided no microphone.
SoundBlaster 16 did not work at all.

I am running Ubuntu 9.04 amd64 with VirtualBox 3.04 and Windows XP guest. With this setup, Rosetta Stone FINALLY worked without a hitch. :)

I hope this information helps someone else - I spent days trying to figure out how to fix this.