You can't mount audio-CDs (they don't have a
file-system), and if they did a cat of the raw device
still wouldn't produce anything sensible.
The difference between /media and /dev is that
/media is a mountpoint (or directory that holds
other mountpoints) while /dev holds raw devices.
In Linux, basically everything is a file (or, more
precisely, a stream) and has a logical representation
of sorts in the file-system, most common examples
are /dev and /proc ...
To tell you how to actually play audio-CDs:
Knowing your distro would help, but in general there's
two possible things to do:
Use xmms (make sure the cd-audio-player plugin is
installed and set-up properly).
Check whether you have an analogue cable going
(internal) from the CD-ROM to your soundcard, and
you should be able to play audio-CDs with any