The Sound of Science

Professor of Physics Thomas Moore receives NSF grant to continue researching the physics of musical instruments.

Ashley Cannaday ’11 and Professor of Physics Thomas Moore examine the physics of stringed instruments. Ashley Cannaday ’11 and Professor of Physics Thomas Moore examine the physics of stringed instruments.

Archibald Granville Bush Professor of Science Thomas Moore has been awarded a new three-year federal grant in the amount of $214,745 from the National Science Foundation (NSF). The grant will support his continued research with undergraduate students in the area of musical acoustics.

The award, part of NSF’s Research in Undergraduate Institutions (RUI) program, is intended to facilitate research by faculty at predominantly undergraduate institutions and encourage educational opportunities for undergraduate students. The award marks the third RUI grant for Moore since 2007, and will fund up to four undergraduate research positions.

“We will continue our work on the physics of the trumpet, and we will investigate the physics of the Himalayan singing bowl,” Moore says. “Current plans also include investigating some interesting aspects of the piano, which we can do thanks to the generosity of the [Rollins’] music department. They donated a piano to our lab.”

The NSF grant has supported eight undergraduate students plus alumna Sarah Zietlow ’06, a local high school teacher. Their work, in collaboration with other students supported by the Student-Faculty Collaborative Scholarship Program, has resulted in eight published peer-reviewed articles with student coauthors and presentations at eight national and international professional conferences. Research has focused on instruments ranging from the electric guitar and the American five-string banjo to the Nigerian slit gong and the Himalayan singing bowl. It all started, however, in 2000 with a trumpet that was donated to the laboratory.

“I was just starting my research in musical acoustics, so we started with the trumpet because that was what I had,” he says. “After reading everything I could about the physics of brass instruments, I discovered that people had been arguing for over 100 years about whether the bell vibrations affect the sound.”

Ask any trumpet player, and they’ll tell you that you produce sound in a trumpet by buzzing your lips together. From a scientific standpoint, this buzzing doesn’t have much of an influence on the valve casings, valve pistons, or the cylindrical part of the trumpet. However, it has a huge impact on the bell, which is the part of the trumpet that emits sound. The buzzing, in effect, creates minute vibrations in the part of the tubing that flares outward at the end of the trumpet that can interact with the sound created by a musician’s lips.

“For many years, it was not clear that minute vibrations of the walls caused by the internal pressure actually affected the radiated sound,” Moore wrote in the grant proposal. “However, in 2005, our group showed that indeed the sound of a trumpet was measurably affected by the vibrations, and that this effect could be significant.”

By using an artificial mouth in place of a musician and by comparing a trumpet where the vibrations of the instrument are restrained to one where they’re not, they found that, in instruments with rapidly flaring bells, the sound produced varies significantly. Trumpets, however, have bends, valves, and multiple braces that get in the way of proving this theory conclusively. So Moore and students are collaborating with colleagues at the Institute of Musical Acoustics in Vienna, which has manufactured two special trumpet bells—each with a different wall thickness—that removes those variables.

“We are very close to proving that we understand the process, and this NSF grant will allow us to take the final step in that investigation.”

More importantly for Moore, however, the grant allows students to participate in research, which he believes is the best way to learn physics. “Although the grant is a research grant, I do research because it is the best way to teach,” he says. “The actual scientific results are of secondary importance. No student can genuinely participate in real research and not be changed. The challenge, the effort, and the satisfaction cannot be replicated in a classroom.”