T he background to this set is somewhat convoluted. Nowadays, we think of La Sonnambula primarily as virtuoso soprano territory. In Bellini's day, however, standard pitch was lower than today, so La Sonnambula was also a vehicle for star mezzos, chief among them Maria Malibran, who, of late, has become a bit of an obsession for Cecilia Bartoli. What we have here, therefore, is the work as Malibran might have sung it. Whether you care for it, however, depends less on your views about performance history than on your response to Bartoli's style, which is so self-consciously moulded as to be mannered in the extreme. There's little here to compete with the thrill of a great soprano such as Joan Sutherland soaring through this music with abandoned ease. And since Bartoli's characterisation consists of variations on girlie breathiness, you'd be better off with Maria Callas's EMI recording if psychological veracity is your primary requirement. The men, however, are rather good, with Juan Diego Florez's suave, uppity Elvino pitted against Ildebrando d'Arcangelo's threateningly charismatic Rodolfo. Period instruments and small-ish choral forces convey real intimacy, though conductor Alessandro de Marchi adopts reverentially slow tempi whenever Bartoli is on the scene.