If you have installed Skype, and sound output doesn't appear to work in Skype at all, then this post may be the solution.
The Skype package that you install on Crunchbang Linux, is a purely 32-bits version. To get it to run, you will have to set up a multi-arch environment. However, even after doing this, Skype will most likely fail to output any sound.
Why? Because the 32-bits version of the PulseAudio library is not installed. For some reason, Skype doesn't notify you of this missing library, and it will silently fail. To fix the issue, run
apt-get install ia32-libs (as root). This will install a bunch of 32-bits libraries, one of which is the PulseAudio library that you need to use Skype properly.
This solution might also work for other distributions, in particular Debian-based ones.
What to do if you tried to fix it yourself, and now Skype is the only thing that can output sound, and everything else fails?
You have most likely changed the default output device for PulseAudio. Because PulseAudio no longer uses your soundcard, Skype can access it directly and thereby occupies the card - and while it would seem to have solved your Skype problem, suddenly everything except for Skype has sound problems.
To fix this, run
pavucontrol, go to the Configuration tab, and set your audio device(s) back to something that says "Analog Stereo" (or something along those lines). You may need to restart PulseAudio (
/etc/init.d/pulseaudio restart) or even your entire system, but your sound should work again.
After restarting PulseAudio and/or your system, simply go to the Skype sound settings, and pick the 'pulse' or 'PulseAudio' audio device from the list. Restart Skype, and the sound for everything - including Skype! - should now function correctly.