Researchers at Georgia Tech have announced that they have been able to determine what makes the acoustics at the Greek theater of Epidauros, one of the best-preserved from the ancient world, so good. They conducted experiments in which they determined that the pattern of seats in the theater effectively filters out low-frequency background noise, such as crowd murmur, leaving higher-frequency sounds such as the voices of the actors in the orchestra, or circular stage of the theater. They suspect that the actors would have been comprehensible even without the lower-frequency tones because of the ability of the human brain to reconstruct missing tones in human speech.
They also hypothesize that the results were serendipitous, and the Greeks did not understand why the acoustics at Epidauros were so good. At least, no extant theater produces such good effects. On the other hand, no theater is nearly as well-preserved, though some have been reconstructed.
My only question with the piece is if they did experiments or modelling to determine what the effect of a packed theater would be on the acoustics. Would the sound waves react off the seats in the same way if they were filled with people?