Greek Amphitheater's Superb Sound Mystery Solved

The theater, dating to the 4th century B.C. and arranged in 55 semi-circular rows, remains the great masterwork of Polykleitos the Younger.
Audiences of up to an estimated 14,000 have long been able to hear actors and musicians—unamplified—from even the back row of the architectural masterpiece.

Now, researchers at the Georgia Institute of Technology have discovered that the limestone material of the seats provide a filtering effect, suppressing low frequencies of voices, thus minimizing background crowd noise.
Further, the rows of limestone seats reflect high-frequencies back towards the audience, enhancing the effect.
However, experiments with ultrasonic waves and numerical models indicated that frequencies up to 500 hertz (cycles per second) were lowered, and frequencies higher than 500 hertz went undiminished, he said.


SOURCE:
LiveScience.com

The builders of antiquity were truly superb architects, even by todays
standards, and it is very cool when we find out exactly how and why
something built thousands of years acts the way it does.


Comments, opinions?

It's not incredible, but it is very neat. I still don't get why people are surprised to learn that humans centuries ago were just as ingenious and intelligent as we are today. They had the same five senses. They had the same big brains and opposable thumbs.

Of course the fact that all their diagrams, blueprints, and discovered were pretty much sent up in smoke in Alexandria when Augustus moved in, and then after the fall of Rome were regarded as "heretical"... I can see how we might be surprised...