On Wed, 18 Sep 2013 23:53:38 -0500, The Daring Dufas
wrote:

Automotive undercoating is available in aerosol cans at most auto parts
stores and it does a fairly good job in damping vibrations and
mitigating noise. ^_^

ISTR, in early days, folks used roofing tar and thinned it with
kerosene in order to paint in on with a brush. I forget _exactly_
what it was used for. Undercoating would seem to apply. I think it was
before you could buy in an automotive store.