If you whisper into the audio focal point, (is that the right phrase?) of a large parabolic dish it can be heard a very long distance away by a person standing at the focal point of a corresponding dish. I wonder whether this concept could be incorporated into the architecture of a building to create an energy free intercom system of sorts. At the right spots in a structure, a frantically screamed "FIRE!" warning could be transmitted at the speed of sound, (minus a few bounces) throughout an entire building, or conversely the security crew could have streaming audio of all of a building's entry points so that in the event of a camera malfunction or tampering, unlawful entries would be guaranteed to be heard in the control room before the system could be sabotaged because it has no power source.

Kinda makes ya wonder if that's why only the king is allowed to sit on the throne eh?
-- 2 fries shy of a happy meal, Aug 31 2004

St. Paul's Cathedral http://www.stpauls....ventDate=02/09/2004
See the reference to the "Whispering Gallery" at the bottom of that page. [Amos Kito, Oct 04 2004, last modified Oct 05 2004]

G EEEENNNIIIUUUUSSSSS.

might be a bit annoying when overhearing everyday conversations, but huge open plan parabollas (especially when everyone has to sit next to the wall) would be great.
-- neilp, Aug 31 2004


There’s an ellipsoidal building where, if you whisper at one focal point, you can be heard at the other.
-- ldischler, Sep 01 2004


Baked by the greek. Their theatres had such a perfect acoustic design that all the audience (even those in the last rows) could hear the actors perfectly.
-- Pericles, Sep 01 2004


There's a pair of spots like this in one of the halls in the US capital building. I couldn't find good info on it online, but from the tour I took many years ago, I remember that some official used to have a desk at one of the spots and didn't realize that someone else was using the other spot to listen in on whispered conversations.
-- scad mientist, Sep 01 2004



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