I recall reading about a professionally built display layout intended for an office reception area that used zip ties to secure the track. Their belief was that even when using homasote or other sound deadening materials, screws would transmit the vibration from the track into the wood base. If I recall, the technique was successful.
I should add that some of us, myself included, like some level of noise from our trains, so I would only try this if your intent was to limit virtually all train sound.
