"Mark" wrote in message
...
I noticed while staying at the Radisson SAS at Stansted airport
recently that even though the whole of one wall is made of glass that
you cannot hear *anything* from outside. No aircraft despite being
only a few hundred metres from the runway, no traffic and no
roadworks.

How soundproof can you make glass and how is it done? I guess it would
be extremely expensive?

From memory, and assuming no gaps or other short-cuts for the sound waves,
sound transmission across a boundary is simply related to ratio of densities
of the air/glass and glass/air interfaces. So the more interfaces the
better, and triple glazing will lower the sound level significantly. It's
rare for there to be no sound leaking gaps in normal buildings, and the
surrounding structure has to be correctly made. (Probably more difficult to
get a decent audio quiet room than one for RF electrical tests, and they're
not easy when 100dB of attenuation is required!).

--
M Stewart
Milton Keynes, UK



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