Seats Helped Ancient Greeks Hear From Back Row
From Wikipedia, the free encyclopedia
Epidauros was a small city (polis) in ancient Greece at the Saronic Gulf. The modern town Epidavros (Επίδαυρος), part of the prefecture of Argolis, was built near the ancient site.
Epidaurus was independent of Argos and not included in Argolis until the time of the Romans. With its supporting territory it formed the small territory called Epidauria. Reputed to be the birthplace of Apollo’s son Asklepios, the healer, Epidaurus was known for his sanctuary situated about five miles from the town, as well as its theater, which is once again in use today. The cult of Asklepios at Epidaurus is attested in the 6th century BC when the older hill-top sanctuary of Apollo Maleatas was no longer spacious enough.
The asklepiaion at Epidaurus was the most celebrated healing center of the Classical world, the place where ill people went in the hope of being cured. To find out the right cure for their ailments, they spent a night in the enkoimitiria, a big sleeping hall. In their dreams, the god himself would advise them what they had to do to regain their health. There are also mineral springs in the vicinity which may have been used in healing.
Asklepios, the most important healer god of antiquity, brought prosperity to the sanctuary, which in the 4th and 3rd BC embarked on an ambitious building program for enlarging and reconstruction of monumental buildings. Fame and prosperity continued throughout the Hellenistic period. In 87 BC the sanctuary was looted by the Roman general Sulla and in 67 BC it was plundered by pirates. In the 2nd century AD the sanctuary enjoyed a new upsurge under the Romans, but in AD 395 the Goths raided the sanctuary.
Even after the introduction of Christianity and the silencing of the oracles, the sanctuary at Epidauros was still known as late as the mid 5th century, though as a Christian healing center.
The prosperity brought by the Asklepiaion enabled Epidauros to construct civic monuments too: the huge theater that delighted Pausanias for its symmetry and beauty, which is used once again for dramatic performances, the ceremonial Hestiatoreion (banqueting hall), baths and a palestra. The theater was designed by Polykleitos the Younger in the 4th century BC. The original 34 rows were extended in Roman times by another 21 rows. As is usual for Greek theaters (and as opposed to Roman ones), the view on a lush landscape behind the skene is an integral part of the theater itself and is not to be obscured.
The theater is marveled for its exceptional acoustics, which permit almost perfect intelligibility of unamplified spoken word from the proscenium or skene to all 15,000 spectators, regardless of their seating (see Ref., in Greek). Famously, tour guides have their groups scattered in the stands and show them how they can easily hear the sound of a match struck at center-stage.
The ancient Greeks in the fourth century B.C. couldn’t have known that they had unwittingly created a sophisticated acoustic filter. But when audiences in the back row were able to hear music and voices with amazing clarity (well before any theater had the luxury of a sound system), the Greeks must have known that they had done something very right because they made many attempts to duplicate Epidaurus’ design, but never with the same success.
The Theater at Epidaurus on the Peloponnese in Greece
Researchers at the Georgia Institute of Technology have pinpointed the elusive factor that makes the ancient amphitheater an acoustic marvel. It’s not the slope, or the wind — it’s the seats. The rows of limestone seats at Epidaurus form an efficient acoustics filter that hushes low-frequency background noises like the murmur of a crowd and reflects the high-frequency noises of the performers on stage off the seats and back toward the seated audience member, carrying an actor’s voice all the way to the back rows of the theater.
The research, done by acoustician and ultrasonics expert Nico Declercq, an assistant professor in the Woodruff School of Mechanical Engineering at Georgia Tech and Georgia Tech Lorraine in France, and Cindy Dekeyser, an engineer who is fascinated by the history of ancient Greece, appears in the April issue of the Journal of the Acoustical Society of America.
While many experts speculated on the possible causes for Epidaurus’ acoustics, few guessed that the seats themselves were the secret of its acoustics success. There were theories that the site’s wind — which blows primarily from the stage to the audience — was the cause, while others credited masks that may have acted as primitive loudspeakers or the rhythm of Greek speech. Other more technical theories took into account the slope of the seat rows.
When Declercq set out to solve the acoustic mystery, he too had the wrong idea about how Epidaurus carries performance sounds so well. He suspected that the corrugated, or ridged, material of the theater’s limestone structure was acting as a filter for sound waves at certain frequencies, but he didn’t anticipate how well it was controlling background noise.
“When I first tackled this problem, I thought that the effect of the splendid acoustics was due to surface waves climbing the theater with almost no damping,” Declercq said. “While the voices of the performers were being carried, I didn’t anticipate that the low frequencies of speech were also filtered out to some extent.”
But as Declercq’s team experimented with ultrasonic waves and numerical simulations of the theater’s acoustics, they discovered that frequencies up to 500 Hz were held back while frequencies above 500 Hz were allowed to ring out. The corrugated surface of the seats was creating an effect similar to the ridged acoustics padding on walls or insulation in a parking garage.
So, how did the audience hear the lower frequencies of an actor’s voice if they were being suppressed with other background low frequencies? There’s a simple answer, said Declercq. The human brain is capable of reconstructing the missing frequencies through a phenomenon called virtual pitch. Virtual pitch helps us appreciate the incomplete sound coming from small loudspeakers (in a laptop or a telephone), even though the low (bass) frequencies aren’t generated by a small speaker.
The Greeks’ misunderstanding about the role the limestone seats played in Epidaurus’ acoustics likely kept them from being able to duplicate the effect. Later theaters included different bench and seat materials, including wood, which may have played a large role in the gradual abandonment of Epidaurus’ design over the years by the Greeks and Romans, Declercq said.