Saw in another thread that someone solves their no-sound issues by editing the config file and changing "sound 0" to "sound 1". Tried that; doesn't help, and the setting reverts whenever I restart the game.
In that thread someone also claimed that the binary links with libpulse, but mine certainly doesn't.
This may be a problem with the distributed libSDL: it sounds like it was built with support for ALSA only, which means it can only talk to PulseAudio if you use the pulseaudio ALSA plugin. Under the general rule 'system libraries always' I erased the distributed libSDL from my copy and relied on my system libSDL, which has PulseAudio support. Sound worked perfectly on this system, which has a hardware-mixing-incapable sound card so is pretty much incapable of producing sound except through PA.
You'll probably find you can produce sound fine if you do the same thing (if you have a systemwide 32-bit libSDL-1.2.so.0 to take its place).
Oh, right, maybe it *does* support PulseAudio then. I misread (given how annoying and fiddly it is to figure out whether a given libSDL supports a given sound driver or not, this does not surprise me in the least).
I have no audio either on Windows 7 x64. I tried to find the config.txt file but I do not think it is included in the build I got from teh Humble Bundle, unless it is a hidden file in a strange location.
I'm using LMDE 64bit.  I went to the /opt/voxatron folder and deleted the libSDL-1.2.so.0 file as I had seen suggested in some other posts I found.  That didn't work, so next I verified that lib32-alsa-lib was installed.  While in Synaptic, I noticed that lib32asound2-plugins was available, but not installed.  I installed the package and then I had sound.  I don't know if the first step is necessary or not, but it's working great without that file, so I see no need to restore it.  Maybe the devs should make lib32asound2-plugins a dependency for the 64bit package.