I used brad sized nails to nail my Microscale track at the track centerline where the cork is split, into the plywood. (Some of my engines weigh almost 15 lb., and run at prototypical speeds, a recipe for track misalignment.) I don't believe that nails this size are significant conduits for noise, but most likely are conduits for vibration (i.e. noise of a different frequency?) imparted to the table. (Noise requires a "cone", i.e. a speaker, to propagate.) I did substantial testing to identify noise sources when running my trains. My layout is in my basement, and I used a decibel meter to measure all of the noise impacts that I could identify. I found that reflected noise upward from the tabletop is one major source of noise. Reducing train speeds helps a lot. I also looked at my drop ceiling for reflected noise, and the ceiling is a contributor. (I made the decision to use "restaurant grade" panels in the ceiling, since I did not want "flakes" falling on my layout. These restaurant panels are used in food service areas in restaurants and have a skim coating to eliminate food contamination. So that non acoustical harder surface reflects noise.) One solution to this is to hang drop "carpets" or other noise absorption materials vertically from the ceiling, but I did not do this. I also determined that noise is reflected upwards from the bottom of the table and upward from the concrete floor. I thought about buying noise canceling rubber/composite sheets and installing them on the underside of the layout tables, but they are pretty expensive and the reduction would only be about 5 dB, so I did not (yet?) do that either. My basement is semifinished, and several pictures in glass frames add to the reflected noise. Noise is measured in dB on a log curve, so a 3 dB reduction in noise results in a one-half reduction in noise "energy", but NOT in perceived noise intensity.
As a result of the above testing, here are my "solutions":
1) Run fewer trains at one time, and run them at a slower speed
2) Turn down the sound on engines
3) Use some inexpensive "area" carpets to reduce noise reflected off a hard floor
4) I am considering acoustical "mats" of the type used for auto sound systems (i.e." boom boxes".)
