THOUGH individual tastes do differ, the market for art suggests that those who have money generally agree on what is best. The recent authentication of a painting by Leonardo da Vinci, for example, magically added several zeroes to the value of a work that had not, physically, changed in any way. Nor is this mere affectation. In the world of wine (regarded as an art form by at least some connoisseurs), being told the price of a bottle affects a drinker’s appreciation of the liquid in the glass in ways that can be detected by a brain scanner.It seems, now, that the same phenomenon applies to music. For serious players of stringed instruments the products of three great violin-makers of Cremona, Nicolo Amati, Giuseppe Guarneri and Antonio Stradivari, have ruled the roost since the 17th century. Their sound in the hands of a master is revered. They sell for millions. And no modern imitation, the story goes, comes close. Unfortunately, however, for those experts who think their judgment unclouded by the Cremonese instruments’ reputations, Claudia Fritz of the University of Paris VI and Joseph Curtin, an American...