Video credit: TU Eindhoven
Ancient Greek theaters — at least three famous ones — do not live up to their claims of perfect acoustics. A team from TU Eindhoven in the Netherlands used advanced acoustical testing techniques to debunk longstanding claims that theatergoers sitting in seats farthest from the orchestra could hear a whispered line.
The acoustical excellence of Greek theaters has formed part of the narrative for tour guides for decades, if not longer. Speaking of the theater at Epidaurus, in 1958 a British archaeologist declared that “even a stage whisper could be picked up by the furthest spectator with the cheapest ticket.” Supposedly the audience could hear an actor who was standing in the orchestra speaking in a whisper.
Faculty member Constant Hak did not experience such exquisite acoustics when he visited Epidaurus, the theater most often praised for its sound quality. This disjunct between experience and accepted fact induced him and a student team to test the theory in Epidaurus, the Odeon of Herodes Atticus and the theater of Argos. The team devised new technology that ensured detailed, accurate measurements.
The new equipment eliminated a problem that reduced the accuracy of previous measurements. Even a slight delay between the time a sound occurs and its recording can distort the measurement. These delays arise from the different clock speeds of the record and play equipment, a problem the Eindhoven team resolved.
The team measured the audibility of multiple sounds (tearing paper, striking a match, dropping a coin, whispering and speaking loudly) in multiple locations and at different times of day. They equipped each theater with 20 microphones and two loudspeakers, placing one speaker in the center of the orchestra and one to the side. Both speakers broadcast a sound that changed from low to high frequency; the slight physical separation created a slight delay unrelated to equipment clock speed.
The results? In some cases, such as the tearing paper, the sound carried but a human sitting more than halfway up the seats could not discern what the sound was. Whispers? No.
“You can certainly hear things, but [the results] are right: if you want to have good speech intelligibility, good perception right up to the last rows, then you need someone who can project the voice,” said Dr. Bruno Fazenda of the University of Salford. Dr. Fazenda also pointed out that the myth of perfect acoustics could arise from “a popular belief that our ancestors had knowledge that has since been lost.”
Even though Dr. Hak’s team has busted this acoustical myth, the theaters themselves are still in occasional use. Their acoustic quality is good, and their settings are as spectacular as the performances.