If you step into a church or concert hall you often immediately recognize the sound, the signature character that helps give these spaces their impact and power.
Now, archeologists believe ancient builders almost 3000 years ago were employing some of the same techniques.
At Chavín de Huántar, a ritual center in the Peruvian highlands, advanced processing and Countryman’s B6 precision microphones are letting acoustic archeologists unlock the sonic secrets of a vanished pre-Inca civilization.
Miriam Kolar, a PhD candidate at Stanford’s Computer Research in Music and Acoustics program and a recipient of a Stanford interdisciplinary graduate fellowship (SIGF), serves as the lead investigator for the Chavín de Huántar Archaeological Acoustics Project.
Since 2008, she has been managing the effort and leading the acoustic investigation with the goal of interpreting the project’s findings in the context of the human perception of sound.
“Chavín de Huántar is a 3,000-year old Andean ceremonial center that encloses a massive stone network of rooms, corridors, shafts, and drains - architecture that has remained remarkably intact since construction ended approximately 600 BC,” said Kolar.
“The project was initiated in 2007 by John Chowning (recognized as the father of FM Synthesis), with John Rick, a Stanford Archaeologist. In 2001, John Rick discovered 20 marine shell trumpets at the site.”
“They were all in one location, were beautifully decorated and remain playable. This was an unprecedented discovery. Suddenly, there was a connection to the musical universe.”
“The archeological thought was that this site was some sort of ceremonial center and we wanted to better comprehend the structure, its sonic character, and its impact on the sensory experience in order to better understand what may have taken place there.”
The microphone array developed for acoustic measurements at Chavín de Huántar consists of 16 Countryman B6 omnidirectional lavaliere microphones.
The application and the manner in which the microphones are deployed is quite unique.
“The B6 is tiny,” said Kolar, “and when you’re making acoustic measurements, you want your equipment to be as small as possible in relation to the sound field because a small mic will alter the sound field less than a large one.”
“With the B6, sound waves of human hearing frequencies won’t scatter, and diffract around the microphone elements. The B6’s frequency response is very flat, it’s durable and moisture resistant, and it has a unique, flexible connector that enables us to manipulate each microphone’s position.”
“So the array, which visually resembles a bouquet of flowers, can be adjusted to measure sound waves from a myriad of points simultaneously.”
“The flexible stem of the B6 made these microphones the ideal tool for this type of application, and in part suggested our configurable array design led by consulting professor Jonathan S. Abel.”
“This stem makes it very easy to adjust the mic’s positioning—enabling us to precisely control where the individual mics are in relation to each other. To make measurements, we put multiple sound sources throughout the space and the microphone array enables us to sample the sound field at high resolution.”
“This arrangement gives us the ability to capture the arrival direction and strength of individual reflections, enabling accurate digital reconstruction of the sound field.”
While the Chavín de Huántar Archaeological Acoustics project is an ongoing effort, numerous findings have already been presented at forums such as Acoustics ’08 in Paris, the Institute for Andean Studies, and AES New York 2009. “This project is a giant undertaking,” said Kolar, “and I’m certain there is much more to discover.”
“Countryman has been extremely supportive of our efforts and has been tremendous in terms of helping us optimize our use of the microphones. The innovative design of the B6 made it the perfect tool as a basis for the microphone array we’ve developed.”
“The diminutive size and flexible stem of the microphone has enabled us to develop a new tool that is perfectly suited to our application. Everyone at Countryman has been extremely responsive and a pleasure to work with.”
Chavín de Huántar Archaeological Acoustics Project
Stanford Interdisciplinary Graduate Fellowship