One trick with fastrack is carpet with a medium high nap it fills the echo chamber base and really cuts down the noise.
Carpet noise fastrack.
Even after doing these things fastrack tends to be a bit louder than traditional track but it makes the noise tolerable.
Homasote absorbs much of the sound that gets through the carpet padding.
In most cases you need to use an underlayment specifically designed for noise reduction between the carpet and the standard pad.
I ve run fastrack on carpeting and it s queiter but to me carpet still lets the sound to escape from under the track.
To eliminate all noise look for a rating that is 75 or higher.
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.