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Full-Text Articles in Mechanical Engineering
Vector Acoustic Intensity Around A Tuning Fork, Daniel A. Russell, Justin Junell, Daniel O. Ludwigsen
Vector Acoustic Intensity Around A Tuning Fork, Daniel A. Russell, Justin Junell, Daniel O. Ludwigsen
Daniel Ludwigsen
The acoustic intensity vector field around a tuning fork is investigated. Theory for a longitudinal quadrupole source predicts a well-defined transition between near-field and far-field, with significant circulation of sound energy in the near-field. Vector components of the time-averaged intensity were measured using a two-microphone intensity probe and found to agree well with predictions from theory. The vector intensity map is interpreted, and shown to provide useful information about the near-field of an acoustic source.
Better Understanding Of Resonance Through Modeling And Visualization, Daniel O. Ludwigsen, Cayla Jewett, Matthew Jusczcyk
Better Understanding Of Resonance Through Modeling And Visualization, Daniel O. Ludwigsen, Cayla Jewett, Matthew Jusczcyk
Daniel Ludwigsen
Students encounter cavity resonance and waveguide phenomena in acoustics courses and texts, where the study is usually limited to cases with simple geometries: parallelepipeds, cylinders, and spheres. Long-wavelength approximations help with situations of more complexity, as in the classic Helmholtz resonator. At Kettering University, we are beginning to employ finite element modeling in our acoustics classes to help undergraduates better understand the acoustic modes of actual structures. This approach to the time-independent wave equation (the Helmholtz equation) was first used in a research and measurements class to investigate two classic resonance problems. The first problem was a study of resonance …
Acoustic Testing And Modeling: An Advanced Undergraduate Laboratory, Daniel A. Russell, Daniel O. Ludwigsen
Acoustic Testing And Modeling: An Advanced Undergraduate Laboratory, Daniel A. Russell, Daniel O. Ludwigsen
Daniel Ludwigsen
This paper describes an advanced laboratory course in acoustics, specifically targeted for students with an interest in engineering applications at a school with a strongly integrated industrial co-op program. The laboratory course is developed around a three-pronged approach to problem solving that combines and integrates theoretical models, computational models, and experimental data. The course is structured around modules that begin with fundamental concepts and build laboratory skills and expand the knowledge base toward a final project. Students keep a detailed laboratory notebook, write research papers in teams, and must pass laboratory certification exams. This paper describes the course layout and …
Constraints On Acoustic Signaling Among Birds Breeding In Secondary Cavities: The Effects Of Weather, Cavity Material, And Noise On Sound Propagation, John P. Swaddle, Caitlin R. Kight, Saji Perera, Eduardo Davila-Reyes, Shena Sikora
Constraints On Acoustic Signaling Among Birds Breeding In Secondary Cavities: The Effects Of Weather, Cavity Material, And Noise On Sound Propagation, John P. Swaddle, Caitlin R. Kight, Saji Perera, Eduardo Davila-Reyes, Shena Sikora
John Swaddle
Increasing evidence suggests that anthropogenic noise from urbanization affects animal acoustic communication. We investigated whether the begging calls of nestling Eastern Bluebirds (Sialia sialis) varied along a disturbance gradient of ambient noise. Contrary to our prediction and the results of a previous study of nestling Tree Swallows (Tachycineta bicolor), we found that nestling Eastern Bluebirds did not increase the amplitude or structural characteristics—including frequency, rate, and duration—of their vocalizations in response to ambient noise. However, we found that prevalent temperature and humidity conditions attenuated begging calls. Specifically, in warmer, more humid weather, vocalizations of nestling Eastern …