ArchaeoacousticsThe Music of the Mysterious Monolith

Miriam Kolar and her Stanford team analyze sound to help reveal the purpose of an ancient "lost city" in the Peruvian Andes.

Half man, half beast, the "lanzón" statue lurks at the center of the complex.
Half man, half beast, the "lanzón" statue lurks at the center of the complex.

In the green upper reaches of the Peruvian Andes, more than 10,000 feet above sea level, lies a mysterious ancient gathering place called Chavín de Huántar. Its stone plazas and temples are now covered in moss, but their grand scale and detailed bas-relief carvings testify to their one-time significance. As with another famous Peruvian site, Machu Picchu, Chavín's exact purpose has long eluded historians and archaeologists because its creators left behind no written records. But while we may never experience Chavín exactly the way the ancients did, archaeoacoustics researcher Miriam Kolar and other sound detectives from Stanford's Center for Computer Research in Music and Acoustics (CCRM A) have shed light on some possible reasons for its existence. Using state-of-the-art technical equipment, they have been able to demonstrate how an engraved stone monolith at the site could have served as a hidden oracle that "spoke" to people listening outside in a sunken plaza.

Half a day's trip north of Lima, at an altitude of 10,430 feet, lies the temple complex of Chavín de Huántar.

Half a day's trip north of Lima, at an altitude of 10,430 feet, lies the temple complex of Chavín de Huántar.

"A person who had access to it would be in the company of a small number of people," says Kolar. When Kolar had the opportunity to conduct sound experiments at Chavín, once a center of spirituality for ancient peoples all over the region, she jumped at the chance. Formerly a sound designer and recording engineer in Los Angeles, Kolar is familiar with how the layout of interior spaces can affect the quality of sound transmission and how a space's acoustics can shape a listener's experience. "Archaeology offers the perfect opportunity to study the human effects of acoustics," she says. "We're interested in the whole ancient landscape of human experience." How might it have been to visit Chavín 3,000 years ago — what might listeners have heard there and what psychological effects might the sound have produced? Kolar's cultural acoustics research seeks to answer these questions

While structures at other noted archaeological sites are often crumbling, the buildings at Chavín still have many interior rooms and corridors intact. Some of the passageways are so narrow and labyrinthine, they make the outside world seem light-years away. "Since these galleries are so deep within the buildings, in many places no light can come in from the outside," says Kolar, as she explains her undertaking.

The corridors and ducts are disorienting and claustrophobic.

The corridors and ducts are disorienting and claustrophobic.

Before Kolar made her first trip to Chavín, her team equipped an archaeologist with a customized acoustics field kit. When taking his first on-site measurements, John Rick employed a compact Neumann loudspeaker to play back powerful test signals in the subterranean chambers. He then used in-ear microphones equipped with Sennheiser KE4 capsules to record the signals, which enabled the researchers to gather information on the sound-transmission qualities of the rooms and corridors. The information was then sourced to develop a digital acoustic model of the galleries.

Kolar, who formed the team together with colleague Jonathan Abel, visited Chavín for the first time in 2008. Once on site, she grew so immersed in recording and analyzing its acoustical properties that she made Peru her research base. "Until you get into the space yourself, you can't really understand it," she says. "Moment to moment, your psychological and physical states alter your perception."

Tenon-heads like these are thought to represent stages of a human-to-feline shamanic transformation.

Tenon-heads like these are thought to represent stages of a human-to-feline shamanic transformation.

As Kolar explored the space, she focused her attention on a sculpture deep inside the temple complex — a 4.5-meter-high stone monolith decorated with fangs and twisting snakes: "el lanzón" or "the lance." She noticed that the carved mouth of this stela was almost perfectly aligned with a corridor and a horizontal duct leading to a sunken circular plaza beyond the temple. Was it possible that this corridor and the two parallel ducts were able to transmit and amplify the sound like some ancient loudspeaker? The recordings made by her on site showed that "there's a direct line of sound from the mouth of the carved monolith all the way to the world outside." Kolar continues, "The question is whether it can be heard there."

To find out, Kolar played test signals from locations near the monolith and in the depths of the gallery using directional loudspeakers. As she hunted throughout the ducts for specific types of sounds produced by every frequency audible to humans (20 to 20,000 Hz), evenly spaced omnidirectional microphones listened in. The results of the data they delivered were amazing: the ancient ducts must have made it possible for sounds emanating near the monolith to be heard loud and clear by listeners in the ceremonial plaza.

Horn of the netherworld: 20 decorated conch shells have been found at Chavín. Carved mouthpieces transform them into deep-sounding trumpets.

Horn of the netherworld: 20 decorated conch shells have been found at Chavín. Carved mouthpieces transform them into deep-sounding trumpets./p>

Just what types of sounds did the ancients make? Since conch-shell horns, known as pututus, appear in much of the site iconography, Kolar's team tested replica pututus on site and also called on famous Peruvian musician Tito La Rosa to perform the instruments in museum tests. Perry Cook led the Stanford team in measuring their natural frequencies and recorded frequencies of around 300 Hz. "If you pass sound from all frequencies in the range of human hearing through the ducts," explains Kolar, "it is fascinating to hear how the sounding-tone frequencies of the Chavín pututus are amplified and high-frequency sounds are drastically suppressed." She suspects the ducts work as filters, making any tone measured at 272 to 340 Hz sound like these Chavín pututus.

Other research indicates that such low-frequency sounds — low enough so that they could be felt as vibrations as well as heard — could have provoked a sense of awe in listeners standing in the plaza. This is because the sounds produced by a conch shell are just as low as those produced by a church organ, the sounds of which believers can not only hear, but feel.

Assuming the decorated stone monolith did serve as an oracle, what was the oracle's purpose? While research is still ongoing, various findings at the site hint at an answer. Archaeologists at Chavín have found pictorial evidence of psychedelic plants like the San Pedro cactus, tools for grinding and mixing plant materials, and representations of people with mucus streaming out of their noses — a typical side effect of using such drugs. The carvings on the oracle statue, including fangs, upturned eyes, and clawed hands and feet, are similar to other carvings found elsewhere on site and in the region, indicating that the statue featured distinctive, possibly religious iconography that had widespread influence.

Archaeoacoustic Miriam Kolar

3 millennia — using a computer, speakers and microphones, archaeoacoustician Miriam Kolar bridges a vast gap in time. The doctoral candidate still doesn't know which deity was worshipped at Chavín, nor exactly by whom. But at least she has found out what the ancients used to come closer to their god: drugs, architecture — and the right sound.

Since Chavín's acoustic environment includes disorienting, sound-distorting corridors as well as ducts that amplify lowfrequency tones, it may have served as the setting for a ritual or ceremony during which people experienced plant-fueled hallucinations. Such visitors may also have heard the haunting low moans of voices or pututus emanating from the oracle where the monolith is concealed. Kolar raves, "We know there's something extremely special about this site. This is a place where people came to have an extraordinary experience." Her team believes priests or other high-ranking officials may have used the oracle to convey messages to visitors outside.

Kolar hopes to continue her work at Chavín, but she also aims to go to other locations to conduct research into other unexplained acoustical phenomena. In the past, she has investigated the sound of Istanbul's Hagia Sophia, the largest and grandest church of sixthcentury Byzantium. For the future, sites such as Hopi kiva buildings in the southwestern United States are on her list. Because, just as the oracle of Chavín softly hums its riddles, the effects of acoustics on human beings still hold plenty of mystery.

The Author

Having visited ruins in Peru as a teenager, author Elizabeth Svoboda was curious to learn how acoustic analysis could illuminate the lives of ancient Peruvian peoples who left behind no written records. Researcher Miriam Kolar — who has spent years at the Chavín de Huántar site studying its former sound landscape – gave Svoboda a fascinating firsthand glimpse into a world where musicians played haunting melodies on shell trumpets and priests broadcast messages to visiting pilgrims via an elaborate network of sound-amplifying ducts. In addition to writing for magazines like Psychology Today, Salon and Popular Science, Svoboda recently completed her first book, titled "What Makes a Hero?: The Surprising Science of Selflessness."