Why does a piano sound like a piano? A similar question can be asked of virtually all musical instruments. A particular note-such as middle C-can be produced by a piano, a violin, a clarinet, and many other instruments, yet it is easy for even a musically untrained listener to distinguish between these different instruments.

A central quest in the study of musical instruments is to understand why the sound of the "same" note depends greatly on the instrument, and to elucidate which aspects o...