Natural Science Forum / Physics / Acoustics / June 2004

You have not specified the thickness or weight per unit area of either the
gypsum or lead, and whether or not the lead is glued to the gypsum.  Myself,
I would rather use two layers of gypsum of significantly different thickness
and comparable overall weight.  Same result for less cost.

    That is an ancient conundrum. The motivating reason for placing lead on
drywall is to "fill" the coincidence dip. The effect on the TL at other
frequencies is negligible. Figure the mass law for the lead at the
2000-3000Hz frequency range, and "fill" the coincidence dip with that
value. How to "add" the two values will be an interesting exercise. If
testing was ever done, it was a long time ago.

Angelo Campanella

I agree with what has been said.

The "Lead Industries Association" used to publish some interesting test
results for using "acoustic" lead sheeting in different constructions.
"Acoustic" lead sheeting is just a euphemism for lead foil. However, don't
know if they are still going.  A Google search should reveal some useful
information though.