Seats helped ancient Greeks hear from back row.(Georgia Institute of Technology)(Brief article)

Scientific Computing, May, 2007

As the ancient Greeks were placing the last few stones on the magnificent theater at Epidaurus in the fourth century B.C., they couldn't have known that they had unwittingly created a sophisticated acoustic filter. It has since remained a mystery, but researchers at the Georgia Institute of Technology have now pinpointed the elusive factor that makes the ancient amphitheater an acoustic marvel.

It's not the slope, nor the wind--it's the seats. The rows of limestone seats at Epidaurus form an efficient acoustics filter that hushes low-frequency background noises, like the murmur of a crowd, and reflects the high-frequency noises of the performers off the seats and back toward the audience members, carrying an actor's voice all the way to the back rows of the theater.