John, Thank you for the tip on watching ebay and Paypal!!
Jeff (ScoutingDad), Jeff the Coaster Guy's study was way more information than I needed to convince me to not worry about screws going through my Homasote and into plywood. I have used a decibel app on my phone to measure sound levels at various places in the church sanctuary a couple years ago. It is still on my phone, but I never thought about using it in the train room. Jeff advanced study was more than I would have done anyway.