Scientists analyze tunes from 3,000-year-old conch-shell instruments for insight into pre-Inca civilization.
- Acoustic scientists played ancient conch shells to understand how they were used 3,000 years ago.
- The eerie sounds may have been used in religious ceremonies.
The music, powerfully haunting and droning, could have been used in religious ceremonies, the scientists say. The team reported their analysis Nov. 17 at the Second Pan-American/Iberian Meeting on Acoustics in Cancun, Mexico.
Listen to the ancient trumpets being played through links at bottom of story.
"You can really feel it in your chest," says Jonathan Abel, an acoustician at Stanford University's Center for Computer Research in Music and Acoustics. "It has a rough texture like a tonal animal roar."
Archaeologists had unearthed 20 complete Strombus galeatus marine shell trumpets in 2001 at Chavín de Huántar, an ancient ceremonial center in the Andes. Polished, painted and etched with symbols, the shells had well-formed mouthpieces and distinct V-shaped cuts. The cuts may have been used as a rest for the player's thumb, says study co-author Perry Cook, a computer scientist at Princeton University and avid shell musician, or to allow the player to see over the instrument while walking.
To record the tunes and understand the acoustic context in which the instruments, called pututus, were played, the researchers traveled to Chavín.
As an expert shell musician blew into the horn, researchers recorded the sound's path via four tiny microphones placed inside the player's mouth, the shell's mouthpiece, the shell's main body and at the shell's large opening, or bell. Similar to a bugle, the instruments only sound one or two tones, but like a French horn, the pitch changes when the player plunges his hand into the bell.
The team used signal-processing software to characterize the acoustic properties of each trumpet. Following the sound's path made it possible to reconstruct the ancient shell's interior, a feat that normally involves sawing the shell apart or zapping it with X-rays.
The researchers also wanted to know how the site's ceremonial chamber, a stone labyrinth with sharply twisting corridors and ventilation shafts, changed the trumpet's sound. To find out, the team arranged six microphones around the musician and reconstructed the sound patterns on a computer.
If the trumpets were played inside the stone chamber in which they were found, the drone would have sounded like it was coming from several different directions at once. In the dimly lit religious center, that could have created a sense of confusion, Abel says.
"Were they used to scare people while they were there?" asks Abel. "There are still a lot of things left open."
Turns out, such questions about how sounds affect people and their behavior, an area called psychoacoustics, can be tested. It's a field of active research, and not just for ancient civilizations: Another group at Stanford is now studying how a room's acoustics affects human behavior. In one recent experiment, researchers separated test subjects into different acoustic environments to do a simple task -- ladling water from one bucket to another in a dimly lit room.
"What your ear can actually hear plays into how you would behave, or the psychological experience in the situation," says Abel.
SHELL CACOPHONY
A group of conch-shell instruments made by a pre-Inca civilization sound similar to a kid learning to play the trumpet. Click here to listen.
ANCIENT TONE
A musician plays the fundamental frequency and the first overtone of a 3,000-year-old shell trumpet unearthed in Peru. Click here to listen.
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