Three approaches to understanding sound radiation from a tuning fork Free

The simple tuning fork has a remarkable pattern of radiated sound. Measuring and modeling this radiation is the ultimate objective of a module designed for our senior-level laboratory course in acoustics. The primary audience for this course is composed of majors in applied physics and engineering physics, as well as engineering students interested in the acoustics minor, mostly electrical and mechanical engineering majors. To complement the blend of students, the course features a careful mix of theory and analytical modeling, computational modeling, and testing. These approaches run through a series of activities emphasizing practical knowledge, including calibrating microphones, validating a finite element model, measuring sound pressure level to produce polar plots of directivity, and using monopoles, dipoles, and quadrupoles to model and predict behavior of several common sources of sound. With these tools, students examine the sound radiated from a tuning fork driven near its lowest resonance frequency. They collect data to create far field and near field directivity plots and use an intensity probe to map 2-D vector intensity in the plane perpendicular to the tines. These are compared with a quadrupole model, as well as the results of a finite element model of their own creation.