My oh my! Audio was always a wierd thing to configure on Linux. Worst it is when you are trying to make it work in an Apple MacBook Pro (MacBook Pro 7,1, Mid-2010, MC374LL/A, A1278 in my very own case). Yet worst when it comes to Slackware Linux, where this particular area is not very well documented as many others distributions out there (don't blame me, Slackers. It's true). When it comes to the audio matter, Slackware Documentation Project, Linux Questions  , Ubuntu Community Help Wiki and Google are your friends, but the best they can do is to give you some clues, Yoda style.