The term "rock opera" has been in use since the late 1960s, but it never really represented a mixture of rock music and opera music; whether it was applied to the Who's Tommy or Green Day's American Idiot, it tended to apply to a rock album with a story line more defined than that of a "concept album." Especially since such albums came to be adapted for the theatrical stage, "rock musical" might have been a better description.

Finnish singer/songwriter Tarja Turunen, on the other hand, does attempt something of a melding of rock and opera on her albums, including What Lies Beneath.

The trained soprano and former lead vocalist of Nightwish demonstrates her intentions on the album's first song, "Anteroom of Death," which alternates classical passages, including a harpsichord, with heavy metal rock and even a touch of the massed vocal arrangements of Queen on a song like "Bohemian Rhapsody." Queen is a good antecedent for Tarja's approach, actually, although her classical side is more classical than classic rock, and her rock side is closer to metal.

She certainly adopts Queen's over-the-top style, filling her English-language lyrics with dramatic overstatement, as suggested by such titles as "Until My Last Breath," "Rivers of Lust," and "In for a Kill." There are quiet, piano-based ballads, but she makes more of an impression on the classical/metal hybrids.

Maybe that's still not quite "rock opera," but it's nearer than the music that has been called that in the past.