OpenAL Soft is a software implementation of the OpenAL 3D audio
API.  OpenAL provides capabilities for playing audio in a virtual
3D environment.  Distance attenuation, doppler shift, and directional
sound emitters are among the features handled by the API.  More
advanced effects, including air absorption, low-pass filters, and
reverb, are available through the EFX extension.  It also facilitates
streaming audio, multi-channel buffers, and audio capture.

WWW: http://openal-soft.org/