An advanced physics laboratory based on the compound string

The compound string is a simple one dimensional system that we are developing as an advanced undergraduate laboratory experiment. Experimentally, the winding of an overwound guitar string is unwrapped to create a discontinuity of the mass per unit length. When plucked at different positions along the string, the anharmonic frequencies of the normal modes create an unusual tone. The experiments to characterize the compound string expose students to high resolution FFT measurements, careful data analysis, and a non-trivial system to practice solving differential equations.