Havn't time to catch up on this thread so this may be redundant - but
43 decibles is the sound level we are asked by env health dept not to
exceed outside our boundary when we set up our joinery shop in new
premises. 43 db being a measurement of the ambient sound in the
neighbourhood and equivalent to a suburban street sound level. Its
actually 43db level equivalent measured over a sample hour. I don't
know if they actually measured it on location or merely took it from
tables.

cheers

Jacob