Beyoncé’s career has always felt like a tightrope walk between big-lunged balladry and pumped-up raunch. On her third solo record, she actually calls attention to this tension. Split between two discs, the album is credited both to Beyoncé and to her sassed-up alter ego Sasha Fierce. But the divide isn’t as clear cut as Knowles seems to believe: Sasha Fierce numbers ‘Single Ladies (Put A Ring On It)’ and ‘Radio’ don’t quite live up to their smokin’ diva billing (the former is essentially a reworked ‘Independent Woman’, the latter a rather sappy ballad) and the supposedly more reserved first CD serves up surprising quantities of auto-tuned kinkiness (‘Halo’, ‘Satellites’). What unites both discs is Beyoncé’s 800-watt charisma: a light that shines through the haze of try-too-hard pretentiousness that might have sunk a lesser performer.