You may or may not know that NASA sprays a bunch of water on the launchpad as a rocket's engines fire. This is done not only to keep the pad from melting, but it also cuts the noise level dramatically. (Even so, if you stood too close to a Saturn V launch, the sound pressure would be enough to liquify your insides.) This video shows the system being used with and without rockets being on the pad. It's interesting that none of the great SF writers who went to great lengths to get the science right (Heinlein rather famously bought a roll of butcher paper to do calculations on to make sure that he got a couple of lines right in Space Cadet) ever mentioned anything like this so far as I know.