I am trying to stay away from the Windows Core API sound since not everyone is on a Windows Machine. Since we are using OpenGL and not Direct X, I am staying away from Direct Sound as well. The ones I'll be listing here will be the most current open source Audio Libraries and Audio APIs that I can find. Some may have 3D audio capability while others may not. Even if one doesn't have 3D Sound capability it could be used as an easy wrapper to just load and read in file streams. I hope this compiled list will help.
Here is what I have found.
Pros: Has many more features then just audio. This library supports many general topics from Custom GUI, graphics, audio, MDI, networking, cryptography, and also supports Audio and Networking plugins.
Cons: Might contain more then what you need, it is not obvious if it supports 3D Sound Environment.
irrKlang by Ambiera
Pros: High level 2D and 3D Cross platform sound engine and audio library that supports many file formats. Ambiera has a few other nice looking libraries and APIs that are useful in 3D game development.
Cons: It does have a free licenses for non commercial use, but for the hobbyist, indie and professional developer there is a license's fee.
Pros: Nice library to manipulate audio and music files. It is well known and well used. Free license for the hobbyist and indie developer if you spent less then $100.00 to develop the game at the time of sales release.
Cons: Requires very expensive commercial use fees.
I have had a hard time finding available free to use open source APIs / Libraries. There doesn't seem to be a big selection out there right now. I am not 100% sure, but OpenAL may come back to the scene under new development since Creative Labs is no longer supporting it. There is a current website that does say they will be back soon. http://www.openal.org/
and as of now there is no return date posted. If worst comes to worse for the individual and not Marek himself, if you so choose you can use the Windows Audio API or the Core API or Direct Sound. I did not list them since this compiled list is for anyone's use but directed towards Marek since they are mostly open source with at least some free licenses agreement and cross platform or multi platform capabilities. I hope this compile list helps you out.
This is a little extra, but a very nice reference site for any game developer that covers many topics in game programming. http://www.gpwiki.org/