On the acoustics of Hellenistic amphitheaters

Hellenistic theaters are well known for their marvelous acoustics. A numerical study reveals that the seat rows of the theater unexpectedly play an essential role in the acoustics, at least when the theater is not fully filled with spectators. The seats, which constitute a corrugated surface, serve as an acoustic filter that passes sound coming from the stage at the expense of surrounding acoustic noise. Whether a coincidence or not, the famous theater of Epidaurus was built with optimized shape and dimensions.