Sounds of past gain presence in archaeology
Tuesday, August 1st 2000, 12:00 am
News On 6
By Alexandra Witze / The Dallas Morning News
Archaeology is a profession in need of a sixth sense.
With sight, archaeologists can spot artifacts sticking out of the dirt. With touch, they feel the sharp edges of shattered ceramics. With taste and smell, they sample the grains and fruits that ancient cultures thrived on.
But they cannot dig up sound.
Instead of using ESP to hear a long-gone world, researchers are devising ingenious ways to study the sounds of ancients. In
new work, archae-ologists are finding how vanished civilizations may have relied on echoes when building their buildings and painting their paintings.
One acoustician, for instance, thinks that the great pyramid at ChichÃ©n ItzÃ¡, Mexico, may have been designed to produce echoes that sound like a sacred quetzal bird. Another scientist has proposed that early humans placed rock art in acoustically significant areas, where booming sounds reverberated dramatically and enriched the art experience.
Such research suggests that modern archaeologists â€“ overwhelmed by the cacophony of traffic, telephones and television â€“ may have overlooked the importance of natural soundscapes.
"What did humans think when they first encountered echoes?" asks David Lubman, an acoustical consultant based in Westminster, Calif. "You couldn't touch and feel and see and taste them, but they were there."
Echoes, he thinks, assumed profound significance for many cultures around the world â€“ including the ancient Maya.
In 1998, while vacationing at ChichÃ©n ItzÃ¡, Mr. Lubman saw tour guides demonstrating the strange sound of a hand clap echoing off the staircase of the 1,000-year-old pyramid of Kukulkan. The sound, he thought, might be more than just a tourist oddity. Perhaps it had significance to the people who built the pyramid.
After making detailed acoustical measurements, he now believes that the distinctive "chirped" echo, which falls in pitch like a high singsong, was designed to sound like the brilliantly feathered quetzal bird.
"If this sound is intentional, it could be the earliest known sound recording," he says.
The shape of the risers, he thinks, was chosen for the chirp effect. Each riser on the pyramid's staircase measures more than 10 inches high â€“ too steep for easy climbing but the perfect dimension to create the chirp.
The distinctive fall in pitch is created by sound energy reflecting differently off the upper and lower steps, Mr. Lubman believes. Some energy reflects first off the nearby lower steps. Other sound waves propagate toward the top of the pyramid, where they take longer to bounce off the steps and return to the observer.
So the higher-pitched sounds from the lower steps return first, followed by the lower-pitched sounds from the upper steps. The resulting echo sounds eerily like the call of a quetzal, a bird that is not found near ChichÃ©n ItzÃ¡ but was sacred to the Maya, Mr. Lubman says.
He thinks the ancient Maya designed the pyramid to make this sound. The staircase has been restored several times, but the ancient version had similar dimensions and was covered in smooth plaster â€“ which would have reflected the sound energy more evenly and sounded more like a quetzal, he says.
"While it could have happened by accident, we should at least realize that the Maya were listeners," Mr. Lubman says.
In fact, the pyramid at ChichÃ©n ItzÃ¡ may have been the focus of one of the world's first multimedia events. Priests may have called on the chirp â€“ the spirit of the quetzal â€“ at crucial points during ancient ceremonies, he suggests.
On the equinoxes, for instance, a serpentlike shadow appears to crawl down the steps of the pyramid â€“ an apparition that attracts crowds of onlookers every spring. The shadow may represent a mystical feathered serpent, the god Quetzalcoatl, who was adorned with quetzal feathers. So the combination of the shadow and birdlike echoes may have created "a magical sound-and-light show," Mr. Lubman says.
But proving this could be tough. David Freidel, a Maya expert at Southern Methodist University in Dallas, suggests that the echo might not be so birdly after all.
"You could say there is some resemblance between bird song oscillations and echoes," he says, "but the Maya would probably not have thought in such terms. They would have prepared such places for people to declare and sing and make music from, but they would not have had a particular bird song in mind."
Still, Dr. Freidel notes, archaeologists have long known that Maya cultural centers have many odd acoustic properties. The great ball court at ChichÃ©n ItzÃ¡, for example, creates unusual echoes. Earlier this century, modern Maya capitalized on these echoes to address their ancestors, who were believed to be buried beneath the ball court.
But the Maya isn't the only civilization that took advantage of strange reverberations. Rock art, in the American Southwest and around the world, may also have been deliberately placed in locations with special echoes or booms, some researchers think.
Steven Waller, a biochemist by day, pioneered this field in 1993 with a scientific paper in the journal Nature. He showed how some paintings in the French caves of Font-de-Gaume and Lascaux are located in parts of the cave with special acoustical properties.
Clap in front of a painting of bison or horses there, for instance, and the echo sounds like thundering hoofbeats. Clap in front of a painting of a cat, and almost no echo returns. In the Nature paper, Dr. Waller suggested that early cave residents might have used sound in their ceremonies, clapping rhythmically to summon game before a hunt.
Since then, he has taken recording equipment to two rock art canyons in Utah and Arizona to try to see whether those paintings were deliberately placed. He has collected anecdotal evidence on the acoustics of more than 150 other rock art sites. He presented some of his results this spring at a meeting of the American Rock Art Research Association.
"He moved it from being a casual, 'Oh wow' observation to something that is more in the nature of a scientific fact," says David Whitley, a rock art researcher based in Ventura, Calif.
In Utah's Horseshoe Canyon, and Arizona's Hieroglyphic Canyon, Dr. Waller discovered that rock art is located only at sites with good echoes. Occasionally, he found a good echo site and then discovered some previously unknown rock art there, painted by the ancients.
"That makes sense if they decorated where they thought the spirits were," he says.
The canyon people probably discovered these sites accidentally, he thinks. While walking along a trail, or searching for water, they may have stumbled across the odd sounds and decided to mark the location.
"I don't think it's realistic to think these ancient people were really scientific and methodical about this," he says.
Nevertheless, the Acoma tribe has a legend about searching for the best echo during their annual migration. According to the legend, they found it close to Petroglyph National Monument in New Mexico, Dr. Waller says.
Sound is just one of several attributes that people may have used to place rock art, says archaeologist Jack Steinbring of Ripon College in Wisconsin. The shape of nearby rock formations, or the way sunlight struck a site, might also have added to the mystical qualities of a place.
Knowing that sound may have been important to ancient people, Dr. Waller and others are working to make sure modern people don't ruin that effect. A visitor center, plopped in the center of a canyon, could destroy the acoustics of certain sites, he warns. Or a major road could bring traffic noise that would disrupt the original sounds, he says.
Modern archaeologists need to imagine themselves back in time, says Dr. Steinbring, and account for the entire environment â€“ including sound.
"We don't have an empathy with the natural surroundings that aboriginal populations have," he says.
To learn more
â€¢To hear echoes from the ChichÃ©n ItzÃ¡ pyramid, visit www.ocasa.org/MayanPyramid.htm.
â€¢Maya Cosmos, by David Freidel, Linda Schele and Joy Parker, is a detailed introduction to Maya mythology and religion (William Morrow, 1993).
â€¢Steve Waller's page on acoustics and rock art is at www.geocities.com/CapeCanaveral/9461.