I'm using Gentoo, but my sound works fine without being a member of the 'audio' group.

harbir, what measures have you taken so far to configure sound? If the answer is 'none' or something similar, I'd recommend you check out the section of the Gentoo documentation that deals with how to install and configure ALSA:

http://www.gentoo.org/doc/en/alsa-guide.xml

If that doesn't work, post back and don't forget to mention what kind of sound card you have and any error messages returned.

-Ch4r