Meeting challenges and facing the music in physics education

The article by Carl Wieman and Katherine Perkins contains an unfortunate error with respect to radiation from violins. The correct multiple-choice answer to “The sound you hear from a violin is produced [by] …” is “(d) none of above.”

Through the bridge, the string’s motion drives the top plate. The top plate’s motion is coupled to the back plate mainly through an internal cylindrical piece of wood, the sound post, which causes the back plate to move as well. That means both plates vibrate, thus both radiate. The violin is a complicated instrument, so it is not easily calculated which radiates more, the top or the back. In fact, the top plate is the stronger radiator. That has been empirically known for more than three centuries, and has been carefully measured by numerous researchers in the musical acoustics field in modern times. Makers pay particular attention to the fashioning of both plates to achieve the best relation between their normal modes.