Page 16 - Engineering Penn State Magazine: Fall/Winter 2020

That Martin Sound
Penn State’s world-class acoustics expertise aids a legendary Pennsylvania company
by Dave Pacchioli and Emily Kissinger
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ENGINEERING PENN STATE
Acoustics has long been an area of strength at Penn State. Expertise in acoustics is a core competency of the University’s Applied Research Laboratory (ARL), one of the top defense-related research labs in the nation. The College of Engineering’s Graduate Program in Acoustics dates to 1965 and remains the only program in
the U.S. that offers a doctorate in the subject. The interdisciplinary Center for Acoustics and Vibration fosters partnerships with industry, bringing all that expertise to bear on practical problems.
Micah Shepherd, assistant research professor of acoustics, and a team of Penn State acoustics experts worked with Martin Guitar to develop a method to analyze acoustic properties of guitars and components—to understand the science behind the variance in sound produced by different guitars and guitar components.
Balancing tradition and innovation
C.F. Martin & Co.®, the family-owned guitar maker in Nazareth, Pennsylvania, has been making acoustic instruments since the 1830s and has always relied on a balance of tradition and innovation to remain the most sought-after acoustic guitar brand in the world.
Partnering with Penn State is one example of the ways in which Martin continues to innovate.
After ARL’s Dave Swanson, an avid guitar player as well as
an acoustical engineer, toured the Martin factory a few years ago, he approached Martin representatives to show them how Penn State could help Martin bring a scientific approach to evaluating the sound of its guitars.
“They have talented musicians who listen to and score guitars on certain metrics—based purely on the sound,” Shepherd said. “What we could offer was a supplement to their current evaluation process—a tool that provides quantitative data that allows them to evaluate whole guitars, as well as guitar components.”
Intrigued, Martin representatives brought several of their high-end guitars to ARL’s anechoic chamber, a cavernous sound-dampened room. There, Shepherd and others wired the instruments with shakers and sensors, buzzed them with white noise, and rapped them with force hammers, carefully measuring the ensuing vibrations. The data they collected established a “vibro-acoustic fingerprint” for each guitar.
“We’re interested in understanding the dynamic properties
of both finished instruments and raw materials, and how that affects tonal qualities,” said Josh Parker, a Penn State alumnus and research and development technician at Martin.
The science of sound
“These real-world applications of our research serve as a win- win for us as faculty members, our students, and our business and industry partners,” Shepherd said. The project—applying Penn State research in a practical setting for an industry partner—fit perfectly with the outreach mission of the Center for Acoustics and Vibration.
For Shepherd and his colleagues, working with musical instruments presented new challenges. Most of the center’s corporate partners, he explained, are looking for ways to minimize vibration.
In the case of a guitar, however, vibration is a good thing— and Martin guitars, in particular, are famous for their resonance.
In part, it is traced to the types of wood Martin has traditionally used: Sitka spruce for the top and rosewood
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