Date of Award
Different instruments can produce sounds that, while at the same frequency, sound very noticeably different to each other. This difference is due to timbre, which is irrespective of pitch, volume, or sound duration. Though not the entire story, one of the main factors influencing timbre is the characteristic overtone spectrum of of the vibration. It is well known that these overtone vibrations are physically present, and they add together to form the final vibration of the object as well as the sound heard. However, it is difficult to perceive the overtone vibrations individually, separate from the fundamental. Using a stroboscope, multiple hypothesized methods to visually isolate harmonic overtone vibrations on a guitar string are tested. By setting the stroboscope in phase with the fundamental, it is shown that any motion seen would be from the overtone vibrations. Measurement of the amplitude caught on video allowed for a comparison to theoretically calculated values using Fourier Coefficients with a sum approximated with Python. Comparison with theoretically calculated values yielded that the amplitude of the overtones was measured to an accuracy of 1.45%. This implies that the motion seen was the result of overtone vibrations and not of the vibration of the fundamental.
Cadiz, Jonathan, "Seeing Overtones: Communicating the Physics of Guitars" (2019). Senior Theses. 1321.