Singer-actress Zooey Deschanel will combine her two occupations this fall on Fox, having written and recorded the theme song to the show she will star in, "New Girl."

Deschanel, known for music-centric films such as "(500) Days of Summer" and "Almost Famous" and who is one half of She & Him, plays a newly single woman who moves in with three guys eager to meet her friends. An overly emotional sort, Deschanel's character sings whenever she is overwhelmed.

"It's just a part of how she expresses herself," Deschanel told the Television Critics' Association Friday in Los Angeles during Fox's panel on the new show. "They're songlets -- they come spontaneously" to the character. The songs she sings are written into the script.

Deschanel says her singing will have a wide stylistic range, from jazz standards and a hefty Ethel Merman vocal style to heavy metal and "a ghoulish voice."

Promotional clips for the show feature the "Dirty Dancing" track "(I've Had) The Time of My Life," both the original by Bill Medley and Jennifer Warnes and by Deschanel and her new roommates who find her alone in a restaurant after she has been stood up.

"New Girl" premieres Sept. 20.

Deschanel said She & Him would continue to work and have recently completed a Christmas album that will be released later this year. Deschanel debuted in the Billboard 200 when She & Him's "Vol. 2" opened at No. 6 in April 2010. That album has sold 217,000 copies to date; "Vol. 1," which peaked at No. 71, has sold 255,000.