Research Bridges Acoustics, Drumsticks and Violins
By Erica Plouffe Lazure
To talk drumsticks with George Bissinger requires a conversation about violins. And to talk violins will undoubtedly lead to a discussion about acoustics and vibration.
In the world of this ECU physics professor, all of these topics are interrelated and are at the heart of his research of the past 32 years.
“The drumstick research is very similar to what I do with the violins. A drumstick is like a one-dimensional violin, without the harmonics,” he said.
A trained violinist, Bissinger said he never really thought about drumsticks until 2004, when he got a call from the Texas-based Pro-Mark drumstick factory.
“They were interested in pitch-matching their drumsticks,” Bissinger said. “It’s easy to do by ear, but they needed an industrial approach, something that could be set up like an assembly line. You can’t have someone sit there and listen to each drumstick.”
Pro-Mark asked Bissinger to apply his work with violin acoustics to testing drumsticks. Bissinger’s work with violins is world-renown, and in 1999 he was awarded a National Science Foundation grant to further his work. The drumstick company mailed Bissinger a box of 100 hickory drumsticks and he set to the task of developing a device using real-time modal analysis that would catch the pitch frequency, or unique vibration, emitted from each drumstick.
“I had come to understand drumsticks pretty well,” he said. “It turns out the drumsticks tend to be about the same, as far as length and weight.”
After putting several drumsticks through a CAT scan, Bissinger found the density and grain of the wood drove the main difference in pitch. He then adapted a device that gauges the pitch of violins to one suitable for a drumstick. Secured only by a pair of rubber bands, and surrounded by tiny microphones, the drumsticks are struck on the tip with a small hammer. The vibrations of the drumstick are then captured by a computer and organized according to their frequency.
“The company needed to know what the range of frequency is,” he said. “The sticks are then put into bins, the low frequency on the left, the high on the right.”
The sorted drumsticks are paired off and sold to the public as “pitch-tested.” It is important to professional drummers, Bissinger said, that the drumsticks are matched, so the sound made when struck is the same. Even holding a drumstick changes its properties, but the pressure applied by each hand is usually similar.
While drummers typically need two sticks that emit similar frequencies when struck, the needs of a violinist are far more complex, Bissinger said.
“The frequency of a violin is key because it enables a hearer to determine its quality of tone,” he said. “I can tell a maker that if they trim a bridge, it will affect the tone. We found that shaving four-hundredths of a gram of wood turned a violin from a very good instrument into a student instrument.”
Bissinger noted that, with violins, what determines a “good” tone is highly subjective. Soloists are looking for different sounding violins than ensemble violinists.
“It is a complex instrument and it doesn’t radiate in ways people traditionally look at an instrument,” he said. The sound a violin makes when its bridge is struck affects internal and external sounds and it is the combination of these sounds resonating that produces the difference in tone, he said.
“It’s part of why the violin sound is so complex,” he said.
Bissinger said the acoustical research could have many implications beyond the demands for fine instruments. He noted that the air and submarine industries are interested in the effect of vibration and he believes the violin could provide a viable “vessel” for applying a theoretical model.
As a musician, however, Bissinger noted that it would be great to produce a chart or matrix that could gauge acoustical elements of fine instruments.
“It may be a nice to develop an acoustic envelope in which all good instruments occur,” he said. “If there are enough modest changes, you could get rid of all the bad violins.”