How many French transplants and Gallic-pop devotees are living in Philadelphia?

We should get a good head count tonight, as two noted French phenoms - Charlotte Gainsbourg and Nouvelle Vague - make appearances at area clubs, forcing fans to make a difficult concertgoing decision.

While just making her Philadelphia debut tonight at the TLA, Gainsbourg is the far more recognizable talent, both for her acting (in such films as "Jane Eyre," "Lemming" and "I'm Not There") and for her history as a torch-bearing cabaret singer.

She comes to both callings naturally. Her father was the daring French pop star/actor Serge Gainsbourg and her mom the British model/actress Jane Birkin.

Together, that pair taught the world just how hot it could get in the boudoir with their sensual international hit "Je t'aime . . . moi non plus." And Serge carried on for decades with an eclectic approach that merged folk, jazz, cabaret and world music influences.

Ears are likely to perk, and caution definitely will be thrown to the wind again next week, as the dreamy-voiced Charlotte and her new production collaborator, the American artist Beck, foist a most intriguing album on the world, surely the raison d'être for her first U.S. concert tour.

Titled "IRM," this trippy, tantalizing art project layers surreal lyrics (mostly in English) with tunes at turns folkish, cabaret and rocking.

It really spins your head around with Beck's sonic playpen of techy studio toys, dramatic world percussion flourishes and eerie, Third Stream/chamber pop strings arranged by Beck's dad, David Campbell.

Beck Hansen takes all the song credits, too. But as Gainsbourg relates, she had lots of input along the way, and just her name appears on the album cover.

"I didn't want Beck to write songs on his side and just give me the melodies to sing," she has said. "I wanted to be involved in the creative process, too. So he ended up creating everything from scratch with me being there. He always progressed according to how I related and what I had to say."

The creative team sensed they were onto something special (and weird) with the very first song they worked on, "Master's Hand."

As Beck relates, "One of the lines I came up with was 'Drill my head full of holes/To let the memories out.' It was a metaphorical image, but afterward the engineer said to me, 'You know that's what actually happened to her last year.' And I had no idea she'd had this accident. We'd never even talked about it." (In 2007 Gainsbourg underwent emergency surgery after suffering a cerebral hemorrhage.)

"Little mysterious things like that - I liked the coincidence," Gainsbourg said. "It had a lot to do with spontaneity and coincidence."

(FYI, the album's clanging, banging title track also references Gainsbourg's medical travails. IRM is the French acronym for what we call an MRI body scan.)

Beck also was thinking some about Charlotte's father during the making of the album.

"Most of the time, I was trying to come up with sounds that would be her own. Which is difficult, because her father covered so much ground . . . Charlotte and I adopted a lot of Serge's North African percussion ideas for our own record."

And while hardly retro, the high-toned aura of Campbell's arrangements hearkens back to the musical era when folkies on both sides of the pond were going "progressive," working with chamber ensembles under the sway of the Beatles.

Tellingly, the label that best served up that music, Elektra, has been dusted off to carry Gainsbourg and Beck's adventurous new millennium music.

Vague is a state of mind

Prefer your French-toasted pop music on the light and breezy side? Nouvelle Vague ("New Wave") is the bubbly champagne to quaff tonight at World Cafe Live. Yet here, too, you'll find the imports throwing us some curves.

Many Nouvelle Vague recordings sound as indebted to balmy Brazilian samba music as they are to Parisian "yeah, yeah" pop. And their special passion (and success) has come with rephrased covers of U.S. and British rock hits of the '80s, like the Go-Go's "Our Lips Are Sealed," Billy Idol's "Dancing With Myself" and the Sex Pistols' "God Save the Queen."

A pretty girl always graces the album cover, and a rotating parade of cooing female singers set the sonic tone. Many of these special guests - like Anais Croze, Camille Dalmais, Phoebe Killdeer and Melanie Pain - are identified as part of the "renouveau de la chanson française" (renewal of the French chanson) movement and have become stars on their own.

But for Nouvelle Vague's latest album, "3," some notable male singers (Martin Gore, Ian McCulloch) get to duet with the girls on tunes sometimes suggesting a more countrified tone.

And it's actually of couple of French gents, Marc Collin and Olivier Libaux, who mastermind le grand affair.

Charlotte Gainsbourg, with Fantasy Square Garden, TLA, 334 South St., 9 tonight, $27.50 (seated, general admission), 877-598-8696, www.livenation.com. Nouvelle Vague, with Clare & the Reasons, World Cafe Live, 3025 Walnut St., 7:30 tonight, $29-$39, 215-222-1400, www.worldcafelive.com.