First, you know you can get the timeline to read in dB under the black down arrow on the left.
You can make the timeline really tall by grabbing the bottom with the mouse and pull down.
Download the Piano Trill from here. It's 6 seconds so we don't have to sit through three minutes to experiment.http://www.kozco.com/tech/soundtests.html
File > Open and put that file on the time line, not Project > Import Audio
. Effect, Amplify and reduce it -24. The blue waveform should all but vanish, although you can still hear it. Export that as a new WAV.
Fresh Audacity. Load the same file. This time normalize to -3 or maximum. You should see the blue waveform expand slightly. Export that as a different WAV file.
Pull both the -24 file and the normalized file into your authoring program (with normalize off) and burn a CD. The -24 file should sound beyond half volume compared to the normalized one. If you almost can't tell the difference, then the burner is "helping" you whether it admits to it or not.