Long before film, video or even recorded sound, there were live performances--without microphones or electric sound systems and with acoustics. Apparently, the ancient Greeks knew a lot about sound.
Researchers from Georgia Tech have solved a puzzle: how was the human voice heard while seated at the back of an ancient stone amphitheater? Research done at the Epidaurus amphitheater shows that in the fourth century B.C., the Greeks were able to build a great theater without understanding sound. And the secret is in the limestone seats.
The rows of limestone filter out low-frequency background noise and reflect the high-frequency sound from onstage voices, so the sound would carry to the back rows. However, later Greek theaters didn't use the same design or seating. So, the apparent brilliant design may have just been a happy accident of site and material.