Consistent wood density is the latest theory that researchers are floating to help explain the superior sound of Stradivarius and other classical Italian violins (PLoS ONE, DOI: 10.1371/journal.pone.0002554). For decades, researchers have scrutinized the antique violins' craftsmanship, including wood treatments and varnishes, to find the secrets behind their rich, resonant tone. Now, Fayetteville, Ark., violinmaker Terry M. Borman and computer scientist Berend C. Stoel of Leiden University Medical Center, in the Netherlands, have examined the wood grains in violins made by Antonio Stradivari and his contemporary, Giuseppe Guarneri del Gesu. Using a computed tomography (CT) scanner, a nondestructive instrument used in medical settings, they compared modern violins to some made by the two masters. The scans revealed that classical violins' wood had less variation in density than that of modern violins. Although differences in wood density do affect sound production, "it would be a mistake to think that it would be enough to reduce the density differential" to recreate the Stradivarius sound, says retired Texas A&M University biochemist and violin aficionado Joseph Nagyvary.