Homasote absorbs much of the sound that gets through the carpet padding.
Carpet noise fastrack.
Finally rather than putting fastrack right on top of a wooden table put a layer of homasote in between the track and the table.
I also used 2 layers of snow blanket on my xmas layout and it helps i ve tested carpet padding on my layout with some of the track on the foam board and some on the carpet padding and the difference is night and day.
Even after doing these things fastrack tends to be a bit louder than traditional track but it makes the noise tolerable.
In most cases you need to use an underlayment specifically designed for noise reduction between the carpet and the standard pad.
50 to 65 percent reduction of noise.
I ve run fastrack on carpeting and it s queiter but to me carpet still lets the sound to escape from under the track.