PulseAudio, previously known as Polypaudio, is a sound server for POSIX and WIN32 systems. It is a drop in replacement for the ESD sound server with much better latency, mixing/re-sampling quality and overall architecture.
A simple volume meter for the PulseAudio sound server.
Not sure what this is supposed to integrate into... everything seems to work the same with and without it(?) Anyway: This package is not necessary for everyday use of pulseaudio.