PulseAudio is a sound server for POSIX and Win32 systems. A sound server is
basically a proxy for your sound applications. It allows you to do advanced
operations on your sound data as it passes between your application and your
hardware. Things like transferring the audio to a different machine, changing
the sample format or channel count and mixing several sounds into one are
easily achieved using a sound server.

Homepage:
https://www.freedesktop.org/wiki/Software/PulseAudio
