It snuck up. In each case it's been unique, resisting category under some blog buzzword or iTunes tag. But it's unmistakable in artists like Marnie Stern and Annie Clark (St Vincent).
There's a new vocabulary emerging for the guitar as an instrument in rock, and the innovation seems to be coming from young women.
Now we can add Anna Calvi to the list.
Arriving to critical bouquets at the start of this year ("PJ Harvey this! Patti Smith that!" the English press expel), she's likely to gain some serious Australasian recognition when she brings her act to Auckland's Laneway Festival next year.
When she offhandedly describes that act as "quite basic - just harmonium, guitar, and drums, really" - things get interesting. You don't walk into the Royal Albert Hall for a charity gig with those three things alone unless you're on top of your game. Which, it appears, the otherwise softly-spoken Malvi indeed is.
How is someone capable of the skyscraping cries of her debut's most chaotic moments?
When pressed about that split, Calvi is almost meek over a phone and doesn't offer much: "It could be just that process of making music - it's so much easier to be strong and fearless in that situation."
Oh, and she only taught herself to sing eight years ago. For the record.
Matter-of-factly, Calvi appears to treat this crash course as sheer necessity. She assigned herself what should have been impossibly lofty targets - "Singers that I love, heroines, people like Edith Piaf and Nina Simone".
As a sporting analogy, this is a bit like someone deciding to try to run as fast as Usain Bolt one day in their early 20s.
She's realistic about the process: "There's definitely some great days along the line where you feel like you've achieved some progress, but it's really a very slow process and it would be hard for me to pick out one huge moment. I mean, there's been moments being on stage where I felt very much that I'm able to access a place that I couldn't access previously."
If she hasn't quite matched her inspirations, she can be forgiven on the basis of her remarkable guitar abilities. Tracks like Rider to the Sea and The Devil start with her playing alone - drizzles of flamenco plucking that blur into a hurricane at a moment's notice.
Unshowily, I'll Be Your Man runs interstices of fractured jazz through the marrow of deadly silent verses. The guitar is where Calvi is, in an odd way, puritanical. "I use reverb, and that's it."
No pedals? Everyone uses pedals. "I like to generate these sounds and effects through what I do with my hands rather than what I might do moving lots of pedals. It's kind of an artistic choice for me to keep the pedals at a minimum."
Live, she attacks the strings with a circular movement - extracting every last tone from the strings themselves rather than transforming them via electronic signals.
Given Calvi's musical pedigree - a degree in the stuff, her first song laid down when she was eight - it all feels a little less daunting when we get back to her influences. That first song was about wanting to be in David Bowie's band. Simple ambition, really.
"The first album I ever bought was Aladdin Sane, and I just always loved his music and just remember being really obsessed with him as a kid, and it's just something that's continued. I love his music and I love how he's very much an artist rather than just a pop singer - he's applying concepts to his music, which I find very interesting."
You can almost hear her blush when the question is posed of whether Bowie's actually ever heard her music.
But laying the facts bare - that his former collaborator Brian Eno appears on her debut doing backing vox, that she was tipped by Ray Davies to appear when he curated England's Meltdown Festival - she's starting to be recognised in these circles.
Perhaps it's only a matter of time.
* Anna Calvi plays St Jerome's Laneway Festival on Monday, January 30 with Feist, The Horrors, Gotye, Laura Marling, Pajama Club, SBTRKT Live, Shayne P. Carter, Washed Out, Twin Shadow, M83, Cults, Girls, EMA, Yuck, Toro Y Moi, Wu Lyf, Glasser, Opossom, The Pains of Being Pure at Heart, Austra - tickets on sale Wednesday 19 October from lanewayfestival.co.nz.
*Questions about Laneway? Ask your question direct to co-promoter Ben Howe in our live chat here.