Some might argue that lack of music in the 1931 Bela Lugosi version of “Dracula” adds to the mysterious atmosphere. Although early sound film commonly had little or even no musical scoring, today this lack strikes us as eerie, even disturbing. In his new score for “Dracula,” composed in 1999, Philip Glass takes away some of this eerie silence. But he also avoids the expressionistic, dissonant style which has become associated with horror movie sound in favor of more subdued, yet subtly unnerving sound. Old movies have recently interested Glass as potential sources. In the early 1990s, he composed an operatic trilogy on three films of Jean Cocteau. Rather than stage the operas traditionally, Glass precisely synchronized them to be performed simultaneously to a showing of the film, as a kind of alternate soundtrack.