Rarely have six basses, eight celli, four trombones and a tuba held more power over listeners. Especially in a movie theatre.

John Williams’s score for Jaws ranks as some of the most terrifying music ever written for the cinema (and, according to a 2005 survey by the American Film Institute, among the top 10 most memorable scores in movie history).

The music of Jaws was as responsible as filmmaker Steven Spielberg’s imagery for scaring people out of the water in the summer of 1975. Its sheer intensity and visceral power helped to make the film a global phenomenon; Spielberg compared it to Bernard Herrmann’s equally frightening, indelible music for Alfred Hitchcock’s Psycho (1960).

The film was only Spielberg’s second feature film as director, as the composer pointed out in a recent conversation at his studio on the Universal lot. The pair had first worked together on Spielberg’s debut film The Sugarland Express (1974).

“I knew about the novel,” Williams recalled. “I don’t think I read it, but Peter Benchley’s book was very, very popular. I remember seeing the movie in a projection room here at Universal....