Looking at the screen for setting audio options you notice that the two sections 		says are called Default Sink and Default Source. These are terms used in the GStreamer 		framework that GNOME uses to describe where data is sent and where it comes from. The 		Default sink is in other words where GNOME apps should output their sound, while 		Default source is where the sound comes from.The reason you might want to alter these settings is because under Unix there are
many different audio systems and sound server which you might want to output to. For
for instance on Linux popular alternatives are the OSS sound system, the ALSA sound
system, the ESD sound server and the ARTSd sound server.For instance if you wish that your GNOME applcations output their sound to the
ESD sound server you set the Default Sink to use ESD. And if you wish that your GNOME
applications which has sound recording capabilities use the OSS sound system to do this
you choose OSS as the Default Source.As mentioned elsewhere in this user guide. These setting are meant for as a tool 		for advanced users who have specialized need. As an ordinary user you should not need
to set these as the vendor of your distribution of Linux or Unix should have set them
for you and sensible defaults.
