Very rarely, Minecraft will start and have all its sounds working perfectly, but most of the time Minecraft will have no sound at all and be super creepy. I still haven't figured out the magic recipe for having sounds.

OpenAL seems properly initialized; it says so in the launcher log that I can't copy-paste because of another bug. So this is not a duplicate of MCL-169.

This happens in 1.6.1 and 1.6.2. I now have the new new launcher, let's call it "the second widget-full launcher". The problem also occurred with the old new launcher, the "first widget-full one".

EDIT:
I uninstalled Pulseaudio, falling back on ALSA only. Now the sound works. This does not solve the issue since every Ubuntu and Mint distribs of the past few years have Pulseaudio installed by default.