The secret's in the seats

Building a backyard Amphitheater anytime soon? Well, the secret is in the seats. Researchers Nico Declercq and Cindy Dekeyser of the Georgia Institute of Technology have discovered the secret to the Greek Amphitheater in Epidaurus.

The theater has 55 rows of seats and is known for its amazing acoustics (acoustics so good, that audience members can hear the unamplified striking of a match at center stage). How is this possible? The porous limestone seats filter out low frequency sounds and reflect high frequencies. This means that the miscellaneous sounds (whispers, shuffling, etc) coming from the audience are suppressed while the higher frequencies of the cast members voices are heard loud and clear. The seats also suppress the low frequency portions of cast members’ voices, but our brains fill those sounds in for us.
Links:
Mystery of Greek Amphitheater's Amazing Sound Finally Solved

Seats Helped Ancient Greeks Hear From Back Row