For Brightman, the voice is the thing

Sarah Brightman kept her singing - if not her costumes - serious. (Yoon S. Byun/Globe Staff)

For a former stage actress who likes to get gussied up like Tinkerbell, engage in faux synchronized swimming routines, and pretend bicycle-ride through sinister forests straight out of Tolkien, you would think Sarah Brightman would have more of a sense of humor. Or sparkling charisma. Or at least some sort of discernible personality.

But Monday night at the TD Banknorth Garden, the petite British diva was all business, focused on only two things: singing and costume changes. The former was incredibly impressive, as Brightman hit glorious highs, belted out robust lows, and mixed up a variety of styles from light opera to pop over the course of the two act, hour-and-45-minute performance. It was all super-serious, full of portentous - and loud - synthesizers providing orchestral flourishes. But there was little variance in mood. A gauzy read of Kansas's '70s hit "Dust in the Wind" received the same furrowed-brow treatment as the churning "Phantom of the Opera" and the soaring "Ave Maria," an achingly beautiful duet with brawny-voiced tenor Fernando Lima from Brightman's recent album, "A Winter Symphony." It was all perfectly pleasant yet strangely polite, like the PBS pledge-drive entertainment it will surely become.

The fashion portion of the show was intermittently entertaining, with Brightman burning through ball gowns and tutus and stilettos like a dress-up-happy 8-year-old. (Although we wouldn't wish the bizarre antebellum hoop mini-skirt with 100-yard-train and lace-up fuchsia leggings on even the most desperate female impersonator.) Apparently there was no room between hitting high C's and negotiating high heels for establishing a rapport with her audience of 4,173 - or with her cadre of backup dancers or the hard-working band hidden behind her whiz-bang stage set. Brightman needn't channel Cher to curry favor, but a smidge more interaction with the crowd - beyond a very proper thanks - or self-deprecation about her fairy princess persona would have warmed the proceedings considerably.

Perhaps Brightman thought the imposing set - complete with an elaborate mirrored video screen capable of transmitting her picture-book 3-D backdrops - would distract from her own low-wattage stage moves, which consisted mainly of strutting down the extended runway, the occasional twirl in billowing skirts, and fluttering arm gestures. She also excelled at lying still on the floor as eight female dancers surrounded her, backstroking their way through routines that would've brought smiles to the faces of Ziegfeld and Esther Williams.