Earlier this month, 43 students from across the world gathered at the University of Mississippi for the 2018 Physical Acoustics Summer School, or PASS.

The summer school began at the Inn at Ole Miss with Greg Swift, a member of the Condensed Matter and Magnet Science Group at Los Alamos National Laboratory in New Mexico, holding an unlit bottle rocket to demonstrate the importance of physical acoustics.

The students, hailing from 16 U.S. and two international universities and countries as far as the United Kingdom and China, gathered from June 3 through 8. During this time, they gathered on campus to discuss various physical acoustics subjects, from thermoacoustics to active noise control.

“PASS is an intensive week where graduate students from around the world get exposed to a wide variety of fundamental topics in physical acoustics taught by world-class experts,” Josh Gladden, UM interim vice chancellor for research and sponsored programs, in a recent news release. “In addition to the broad technical knowledge, [the school] provides a wonderful opportunity for the graduate students to form relationships with their peers and professionals in the field. As a PASS 2000 graduate, I still keep in touch with my classmates.”

Later during his demonstration, Swift pulled out a blowtorch and heated a glass tube, recreating the “singing tube,” an invention by Charles T. Knipp. A longtime University of Illinois physics professor who died in 1948, Knipp was well-known for his experiments in rainmaking and the conduction of electricity through glass.

Glass tubes are often used to showcase the conversion of heat energy into sound through a vibrating air column.

Early on, he told the group members that he expected them to participate and peppered his presentation with questions such as “Why do some of these bottle rockets whistle?” “What’s the meaning of the question: Why does it whistle?” “What’s the scientific approach to a puzzle like this?” “What is still missing from our explanation here?”

Students gradually worked through an explanation of why a whistling bottle rocket whistles that involves the bottle rocket’s pyrotechnic composition, shape and combustion dynamics.

In addition to Swift’s bottle rocket experiment, the school also included six more presentations, covering topics such as the acoustics of bubbles and bubbly fluids, biomedical ultrasound and active noise control.

Scott Sommerfeldt, a professor in the Brigham Young University Department of Physics and Astronomy, hosted a session on active noise control. During the lecture, Sommerfeldt posed more questions to the students.

“Where did the energy go?” he asked during the lecture. “Are we violating physics here?”

Sommerfeldt is researching methods for reducing unwanted sounds by matching sound against sound to create silence, according to a news release from the university.

The research has practical applications from quieting noisy propeller-driven aircraft to hushing air-conditioning systems and office equipment. His talk ranged from an introduction to inventor Paul Lueg, a German generally credited with beginning active noise control in the 1930s, to modern research into noise-cancellation methods.

The students and lecturers also spent an afternoon touring the National Center for Physical Acoustics. Located on the Ole Miss campus, the NCPA began in 1986 and serves as the physical acoustics archives for the Acoustical Society of America and coordinates the biennial school.

According to Gladden, this year’s camp was quite a success. Gladden has seen some success in the field as well, having recently been elected as a fellow of the Acoustical Society of America for his service to and leadership in the field of physical acoustics.

“Having PASS on the Ole Miss campus gives us the chance to show off our physical acoustics facilities right here in Oxford,” he said in a news release. “Students got to see cutting-edge acoustics research and ask senior scientists detailed questions.”