OpenAL Soft is described as 'LGPL-licensed, cross-platform, software implementation of the OpenAL 3D audio API. It's forked from the open-sourced Windows version available originally from the SVN repository at openal.org'. There are seven alternatives to OpenAL Soft for a variety of platforms, including Mac, Windows, Linux, Android and iPhone. The best alternative is PortAudio, which is both free and Open Source. Other great apps like OpenAL Soft are Wwise (Freemium), RtAudio (Free, Open Source), FMOD Ex (Free Personal) and OpenAL (Free, Open Source).
RtAudio is a set of C++ classes that provide a common API for realtime audio input/output across Linux, Macintosh OS-X and Windows operating systems. RtAudio significantly simplifies the process of interacting with computer audio hardware.
OpenAL is a cross-platform 3D audio API appropriate for use with gaming applications and many other types of audio applications. This is the Creative Labs implementation and is bundled with Creative drivers.