Renée Fleming has never been content merely to rest on her laurels. Recent albums have found the renowned American soprano branching out from the repertoire with which she first gained fame to tackle the high-wire coloratura of bel canto opera and the more intimate expressive demands of Handel's arias. Haunted Heart is no less bold -- nor intimate -- but it is an experiment of an entirely different kind: It's an eclectic mix of popular songs, ballads, and standards, exquisitely accompanied by jazz maestros Bill Frisell on guitar and Fred Hersch on piano. Striking a quietly introspective mood at the outset with the gorgeous title track, Fleming wraps her creamy vocals around such diverse pop classics as Stevie Wonder's "My Cherie Amour" and Lennon & McCartney's "In My Life" while also pulling in standards like Steven Foster's "Hard Times Come Again No More" and even Gustav Mahler's "Liebst du um Schoenheit," which, thanks to Fleming's impeccable diction and vocal skill, comes off as one of the album's finest tracks. Anyone who read Fleming's down-to-earth memoir, The Inner Voice, knows the importance of pop to the young singer's budding career, before she felt the pull of the opera stage. So Haunted Heart is something of a home-coming for Fleming. Yet it is also suffused with an appealing melancholy that seems all the more authentic coming from a performer who's been around the block, reached the top of her field, and has nothing left to prove. Critics on either extreme may find fault with Fleming's delivery -- her "classical" precision at the expense of a more natural, poplike approach or, on the other hand, her holding back so much on her full operatic voice to achieve a close-miked intimacy. Never mind them. Haunted Heart reveals yet another side to an exceptional artist who, refusing to be pigeonholed, finds success wherever her adventurous spirit takes her. EJ Johnson