Are three chords still enough?

Where have all the rock girls gone?Courtney Love is a shattered mess. Liz Phair hired the Matrix and went adult-contemporary. Sheryl Crow is retreading Cat Stevens. The quarterly magazine Rockrgrl, which profiles women in rock, has been reduced to showcasing Kelly Osbourne on its cover.

Alanis Morissette? Avril Lavigne? Sorry. They’re Pat Benatar and Pat Benatar Jr.

We’re looking for P.J. Harvey.

The older gals — pardon the ageism — are doing what they can. Blondie’s Debbie Harry and the Pretenders’ Chrissie Hynde still write and record new songs. Stevie Nicks is full time with Fleetwood Mac again. But one can’t reclaim the torch once it’s been passed.

Here and there, young indie rock has its female faces. They often don’t have the decency to go by their real names: the Kills’ VV (aka Alison Mosshart), the Yeah Yeah Yeahs’ Karen O (aka Karen Orzolek).

And you can often find them on drumseats: Meg White of the White Stripes, Janet Weiss of Sleater-Kinney and Quasi, and the astonishingly young Rachel Trachtenberg (she’s 10 and plays for her dad).

There’s the promising “it girl” Joss Stone, an English teenager with a voice to reckon with, but her thing is neosoul. The former teen-popper Pink is a rock convert but, at this point in her career, barely more than a dilettante.

Popular and underground rock are dominated by the boys — by dudes such as Miss White’s ex-husband, Jack White.

The girls, meanwhile, are Nickelodeon nullities (Hilary Duff) or glorified dancers who happen also to sing. Some have good voices (Christina Aguilera). Some have bad voices (Britney Spears). Anyway, the voices are incidental to the flesh.

For some reason, female rockers have gone missing.

The women who matter on today’s music scene have outgrown rock. Their male peers have yet to catch up with them, but then, girls do grow up faster than boys.

The women who matter today are playing music that’s older than rock, albeit sometimes with a rock sensibility.

They’re the girls of pre-rock-post-rock.

Or something like that.

Consider the likes of Nellie McKay, Norah Jones, Amanda Palmer and Diana Krall.

Each prefers piano over guitar. Their voices soothe rather than abrade. Their influences had their heydays before the Beatles deplaned in New York, before Elvis shook his hips.

At 20, Miss McKay is a voracious assimilator of pre-rock: Tin Pan Alley, cabaret, Doris Day-like vocal pop. She’s also into hip-hop, making her one of the oddest and most restorative voices in music today, male or female.

Miss Jones is becoming steadily comfortable with the rock form, but her heart is with popular jazz and old country, from Hoagy Carmichael to Hank Williams. The unlikely success of her first album has been matched by brisk sales of her sophomore effort, “Feels Like Home,” which straddles Duke Ellington and Dolly Parton.

Miss Krall, a jazz pianist, got her start singing standards. Her new album, out next week, is her first stab at original material, which was co-written with her husband, Elvis Costello, who, as it turns out, has a pre-rock jones of his own.

The wild card here is Miss Palmer, of Boston’s Dresden Dolls. Attitudinally, the Dolls are a punk band. Yet Miss Palmer, the player, is firmly pre-rock. Her inspirations are children’s music, show tunes and Weimar-era cabaret.

Even more interestingly, Miss Palmer, in her early 20s, has unearthed the pre-rock singer-songwriter Jacques Brel, a Belgian Frank Sinatra who had no need for a Cole Porter. His songs have been covered by artists as varied as Dionne Warwick, David Bowie and Neil Diamond.

And the Dresden Dolls, who covered his “Amsterdam” at a recent appearance at Arlington’s Iota Club and Cafe.

This company of females competes for attention at a time when the headline-grabbing male rock is concentrated in New York and derivative of the late-’70s/early-’80s punk and New Wave scenes.

In other words, been there, done that.

These gals have taken on a much tougher job. Tougher because popular music before the rock world of electric amplification — can’t have feedback without it — was one of greater technical skill.

Chuck Berry’s guitar-playing was, in retrospect, quite revolutionary. But jazz pioneer Charlie Christian could have done “Johnny B. Goode” left-handed.

Miss Krall’s husband will be the first to tell you: Learning to compose on the piano and write string arrangements demands infinitely more proficiency than, say, the simple descending riff of “Pump It Up.”

The pre-rock-post-girls have reminded us that the trajectory of popular music from big band and jazz to three-chord rock ’n’ roll was one of devolution.

The Beatles were considered sophisticated. They were, but only in the context of early rock. John, Paul, George and Ringo would’ve been snickered out of an audition for Benny Goodman’s band. (He didn’t need singers, you know.)

Nellie McKay, Norah Jones, Amanda Palmer and Diana Krall are not merely rock girls. Possibly, they’re far better.

These women are seriously talented. Which means they’ve raised the bar for rock, without succumbing to the excesses of “progressive” rock.

Take note, boys, and grow up.