The shape of the belly and back may be compared to an arch that withstands and distributes the pressure of the bridge on the belly. The shape of the arch controls the tone of an instrument. Amati and Stainer built highly arched instruments, and Stradivari's early instruments all still have a fairly high arch as well. His later instruments, however, exhibit lower arches.

Three violins, arching profile and thickness graduation in comparison. Micro CT-scan