In article , Ziggur
writes

A sealed unit composed of different glass thicknesses on either side of
the air gap is a common method of noise reduction.

See:-

http://www.pilkington.com/Asia+and+A...English/Buildi
ng+Products/Householder/SmartGlass+Solutions/Reduced+Noise/Reduced+Noise
+
Facts+and+Figures.htm

That's amazing, the 19 to 46% jump from simple DG to lam & 4mm is
quite something aaand with only an 8mm gap. Hopefully the laminated is
on the inside which would be a security enhancement but that may mean
no low-E.
--
fred