CD reviews: Christina Aguilera, Taio Cruz

Christina Aguilera, "Bionic" (RCA)

Aguilera has a formidable voice, her pick of collaborators and a catalog of songs she wrote, many of them about a woman's self-determination. Now, she has decided to present herself mostly as a sexbot: a one-dimensional hot chick chanting come-ons to club beats.

For Aguilera, 29, it's an artistic swerve, turning away from the soul-flavored songs on her two previous albums to visit the electronic realm. But the choice makes her sound as peer-pressured as a pop singer can be. This is the way to ringtone sales and radio play, until the next sexbot struts off the assembly line.

Instead of separating herself from the pop-R&B crowd with her bluesy voice and her tales of trauma and redemption, Aguilera plays catch-up. She goes breathy like Britney Spears; she bounces vocals against percussion like Beyonce. In the S&M-styled video clip for the album's first single, "Not Myself Tonight," she changes costumes as frantically as Lady Gaga.

The tracks dip into reggae, electro and disco revival. They're snappy, gimmicky and professionally catchy; "Elastic Love," written with M.I.A., has a low-fi core and lyrics that cleverly work office-supply metaphors. But the songs are built for narrower voices; they barely need Aguilera. The second part of the album finds Aguilera in grown-up mode for a handful of ballads. She confesses to insecurities in "I Am" and holds back tears in "You Lost Me."

The CD is summed up when Aguilera advises in "Glam": "Be superficial -- it's your one shot." She spends "Bionic" acting as if that were true.

JON PARELES, NEW YORK TIMES

This British R&B-pop star's U.S. debut mostly features songs from his first two British albums, released in 2008 and 2009. Cruz, who produced every track on this album save one, works at the intersection of R&B and electronic music, taking the digital soul of T-Pain and The-Dream to extremes that make even borglike competitors like Jason Derulo appear earthy.

But the older songs here are gentler in subject matter, attitude and volume than the more recent ones, which have made Cruz something of an instant pop star. "Break Your Heart," which has already reached No. 1, manages to be airy while abusive synths descend from every corner. It's probably the most optimistic song about romantic malfeasance in recent memory.

Most of "Rokstarr" chugs along like this, though with less cynicism, fully mechanized and overflowing with empty calories. It's exhilarating and exhausting, and ultimately memory-depleting. Harsh, bombastic synths imported from megaclub trance music give these songs (particularly "Take Me Back" and "No Other One") motion and heft, and Cruz, or his voice box approximant, brings sweetness. There are vapid lyrics to navigate but they don't disrupt the mood, which is emphatic and rarely sensual: Turns out Cruz has no off switch.

JON CARAMANICA, NEW YORK TIMES