CS6 Audition 'burn audio to CD'

It's not quite as simple as that. For a start, you might have noticed that if you don't have a recordable CD in the drive, it doesn't actually report any speeds at all as being available to use. One reason for this is that when you put a blank disc in it, it does a rapid check in a small area near the run-in to see what can actually be written to it, and it won't report until that's happened (it's a pretty quick check, so you don't notice it's happening). The second thing to note is that the reported speed, and what actually happens, don't correspond anyway; the writing speed varies across the disc, as a rule -  quite widely.

This is a pretty complex subject, one way or another, and it doesn't work the way most people think it does at all. There are loads of articles about it, but if you want a very basic indication in English, not jargon, of what happens, then look here: CD burning — the speed you need - PC World Australia