FMOD A sound system on Windows, Linux and Windows CE, PS2 and XBox. http://www.fmod.org/

BruteFIR A software for applying long FIR filters to multi-channel digital audio, either offline or in realtime. http://www.ludd.luth.se/~torger/brutefir.html

ALSA (Advanced Linux Sound Architecture) An audio library (and kernel level API) for Linux. http://www.alsa-project.org/

Ethan Brodsky's Sound Programming Libraries Sound libraries for the PC-DOS platform. http://www.cae.wisc.edu/~brodskye//

Virtual Sampler SDK Provides applications running on Pentium-class PCs under MS Windows 9x/NT/2000 with a MIDI-controlled, low-latency, fully programmable wavetable module implemented entirely in software. [Commercial] http://www.polyhedric.com/software/vssdk/

DUMB - Dedicated Universal Music Bastardisation A high-quality IT/XM/S3M player library. Versions 0.9+ will have MOD support. An add-on is available for playing OGG files. [Freeware] http://dumb.sourceforge.net/

GSI (General Sound Interface) An audio system with network support and provides the ability to use stereo, 3D audio, doppler effects, music playing (MIDI, HMP, MUS), and cd playing and ejecting/changing. [Open source, BSD License] http://gsi.sourceforge.net/

Digital Room Correction DRC generates digital room correction FIR filters to be used within HiFi systems in conjunction with real time convolution engines like BruteFIR. [Aladdin Free Public License (AFPL)] http://freshmeat.net/projects/drc/?topic_id=114

Spark A sound engine for Windows. It provides powerful sample, streaming, and module playback functions and can be used with and without DirectSound. It distributed in two forms: static (.lib) or dynamic (.dll) libraries. http://web.axelero.hu/egzo/spark/

DMM_Volume_DLL The control of volume is realized by the u32 library. The library can work in all the MS Windows versions (95, 98, ME, NT, 2000 and XP). [Commercial] http://www.dmm.cz/en/dmm_volume_dll.htm

OpenAL A free (LGPL-ed) and open source, cross platform audio library used for 3D and 2D sound. http://www.openal.org/

Microsoft DirectX Microsoft's gateway on DirectDraw and the rest of DirectX. http://www.microsoft.com/windows/directx/default.asp