Audio related software.  Includes public domain, free and research related.

OPEN AL:  OpenAL, the Open Audio Library, is a joint effort to create an  open, vendor-neutral, cross-platform API for interactive, primarily  spatialized audio. OpenAL's primary audience are application developers  and desktop users that rely on portable standards like OpenGL, for games  and other multimedia applications. OpenAL is already supported by a number of hardware vendors and developers.
   http://www.openal.org/about/

WaveSurfer.  An Open Source tool for sound visualization and manipulation.  It can be used as a stand-alone tool suited for a wide range of tasks in speech research and education. Typical applications are speech/sound analysis and sound annotation/transcription.
   http://www.speech.kth.se/wavesurfer/

VRML Audio Tutorial.  Guide to learning how to implement sound in VRML 2.0 files. Assumes reader is familiar with VRML 2.0. Cosmoplayer is needed to view and hear the examples.  Also includes some VRML sound related links at the end of the document.
   http://www.dform.com/inquiry/tutorials/vrmlaudio/

MFFM 3D Audio Library by Matt Flax.  This library is for driving 3D speaker arrays.  Library will specify the amplifier gains (volumes) required for each speaker in a 3D audio array, to perceptually place a sound source at a particular location in space.  Operates in real-time.  According to the author, its the first library of its kind!
   http://mffm3daudiolib.sourceforge.net/