AS symbolic shifts go, two recent events in pop music couldn’t have been more illuminating. On Nov. 24 “Burlesque,” a big-screen musical starring Christina Aguilera, opened and landed with a thud, both critically and at the box office. On Dec. 2 came the Grammy Award nominations. Among releases up for the album of the year award are those by Lady Gaga and Katy Perry; Ms. Aguilera, who also released an album, “Bionic,” in 2010, was ignored.

Such turnover is part of pop’s constant process of renewal: out with the old idols, in with the new. But the ground shifted under pop in an even bigger way. As seen and especially heard in “Burlesque,” Ms. Aguilera has been one of the foremost practitioners of the overpowering, Category 5 vocal style known as melisma. The female pop stars who have dominated the charts this year rarely opt for that approach. Their ascent makes it clear that melisma has retreated, while pop, which has just wrapped up one of its best years in at least a decade, has benefited from a return to less frilly, less bombastic vocal showcases.

Although there’s nothing simple about it, melisma in its simplest form is a vocal technique in which a series of notes is stretched into one syllable. Its roots can be tracked back to gospel, blues and even Gregorian chant; Ray Charles, Aretha Franklin and Stevie Wonder used it sparingly early in their careers.

But beginning two decades ago, melisma overtook pop in a way it hadn’t before. Mariah Carey’s debut hit from 1990, “Vision of Love,” followed two years later by Whitney Houston’s version of “I Will Always Love You,” set the bar insanely high for notes stretched louder, longer and knottier than most pop fans had ever heard. A subsequent generation of singers, including Ms. Aguilera, Jennifer Hudson and Beyoncé, built their careers around melisma. (Men like Brian McKnight and Tyrese also indulged in it, but women tended to dominate the form.)