Menlo Park, CA â€“ July 2010â€¦ Step into a church or concert hall and you immediately recognize the soundâ€”that 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 ChavÃn de HuÃ¡ntar, a ritual center in the Peruvian highlands, advanced processing and Countryman’s tiny B6 precision microphones are letting acoustic archeologists unlock the sonic secrets of a vanished pre-Inca civilization.
Miriam Kolar, a PhD candidate at Stanfordâ€™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 ChavÃn de HuÃ¡ntar Archaeological Acoustics Project. Since 2008, she has been managing the effort and leading the acoustic investigation with the goal of interpreting the projectâ€™s findings in the context of the human perception of sound. She described the nature of the endeavor.
â€œChavÃn de HuÃ¡ntar 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,â€? Kolar explained. â€œThe 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.â€?
The microphone array developed for acoustic measurements at ChavÃn de HuÃ¡ntar consists of 16 Countryman B6 omnidirectional lavaliere microphones. The application is unique, as is the manner in which the microphones are deployed. Kolar discussed the microphone, its reason for being selected, and how the array is configured.
â€œThe B6 is tiny,â€? Kolar notes, â€œand when youâ€™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 wonâ€™t scatter, and diffract around the microphone elements. The B6â€™s frequency response is very flat, itâ€™s durable and moisture resistant, and it has a unique, flexible connector that enables us to manipulate each microphoneâ€™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.â€?
â€œThe 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,â€? Kolar continued, â€œThis stem makes it very easy to adjust the micâ€™s positioningâ€”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.â€?
While the ChavÃn de HuÃ¡ntar Archaeological Acoustics project is an ongoing effort, numerous findings have already been presented at forums such as Acoustics â€™08 in Paris, the Institute for Andean Studies, and AES New York 2009. â€œThis project is a giant undertaking,â€? notes Kolar, â€œand Iâ€™m certain there is much more to discover.â€?
Kolar summarized her experience with the Countryman B6 microphones, â€œCountryman 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 weâ€™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.â€?
For additional information about the ChavÃn de HuÃ¡ntar Archaeological Acoustics Project, visit site at https://ccrma.stanford.edu/groups/chavin/. To learn more about the Stanford Interdisciplinary Graduate Fellowship, go to http://vpge.stanford.edu/SIGF/index.html.
About Countryman Associates
For more than 30 years, Countryman has focused on developing microphones and accessories that deliver maximum gain before feedback, with the highest possible rejection of wind, vibration, interference, and other unwanted sounds. The result is warm, clear vocals in speaking and singing applications, delivering natural audio reinforcement that requires almost no attention from the sound engineer or the performer. For additional information about Countryman Associates, visit the company online at www.countryman.com.
Photo info: Image of Miriam Kolar with the Countryman B6 microphone array.