When Beyoncé does something, she does it big. When Destiny’s Child first belted their way into the music world, they announced themselves with unstoppable hits like “No No No.” When she dropped her first solo album, “Dangerously in Love,” it debuted at number one on Billboard and sold over 4 million copies. She began her film career opposite Mike Myers in “Goldmember,” and then earned a Golden Globe nomination for her role in “Dreamgirls.”

But “4” is different. Though the Beyoncé singing on “4” is still the strong, independent woman of “I Am...Sasha Fierce,” many of her new songs focus on her wholly committed lifestyle, most recently confirmed by her pregnancy. On “1+1,” the first love song on an album filled with expressions of love and commitment, Beyoncé croons that “If I ain’t got nothin’ I got you,” a marked departure from “If you liked it then you should’ve put a ring on it.” Her crystal-clear high notes on the word “you” only emphasize the depth of her affection, and set the otherwise standard, solid ballad apart. “1+1” establishes the themes of romantic commitment and loving companionship that she dutifully follows throughout the album, which sometimes feels like one long love song.

On “The Best Thing I Never Had,” Beyoncé stops celebrating monogamy to deliver a triumphant breakup song. The song signals a break between the sentimentality of the first few songs and the idiosyncratic funk of the rest of the album. The song benefits from the use of backup vocalists to sing the chorus. At moments, Beyoncé’s strong soul voice disappears and is replaced with a sweet soprano chorus that reiterates that he was the “best thing [she] never had.” The effect makes her voice cut even more sharply through lyrics like “thank God you blew it,” and gives an angelic quality to the otherwise bitter theme.

The real fun begins about a third through the album, with the old-school jam “Party” featuring André 3000. This solidifies the change from Beyoncé’s standard style to an almost indie-retro turn. The funky beat and André 3000’s smooth talking hearken back to the days of boombox hip-hop, and, although she did not recruit any famous saxophone players like Lady Gaga and Katy Perry recently have, “Party” is clearly a tribute to the great musicians and styles of the past.

“Love on Top” also uses the signatures of old-school R&B and soul, but Beyoncé outdoes her predecessors with not one, but four voice-bending key changes. She holds her own through each shift and sells the song, but even her phenomenal voice can only carry a fairly repetitive tune for nearly 4 and a half minutes. “Love on Top” has a great brass section and a very talented chorus of back-up singers, but the song tries to keep the party going for just a little bit too long.

The album’s sonic diversity is only expanded by the almost military drumlines of “Countdown,” “End of Time,” and “Rule the World.” “End of Time” and “Rule the World” are both brawny, stripped-down anthems to girl power, each of which work well on their own, but become redundant when played in succession. “Countdown” is the most confusing song of the album—the vocals soar as if it were a love song while a brass band plays a funky march—but also the most compelling. It may not be especially aesthetically pleasing—the transitions between the hyperactive parts are slightly jarring—but it serves as a neat metaphor for the experimentation of the album—and her career—as a whole.

Beyoncé is in top form on “4.” Although it may not be perfect, the album captures the singer at a moment of artistic maturation. Beyoncé has clearly settled into her role as the queen of R&B, and seems to feel more free to experiment with both new and old styles. This transformation suits her.

—Staff writer Sara Kantor can be reached at skantor@college.harvard.edu.