JOHN YANG: In today's pop music, vocals reign supreme.

The charts are dominated by singers and rappers, but there's an increasingly popular genre focused more on instrumental music.

William Brangham recently caught up with one of the bands at the forefront of this movement.

WILLIAM BRANGHAM (voice-over): This Texas trio, with their airy and dreamy sound, are one of the most unlikely musical sensations.

Guitarist Mark Speer, bassist Laura Lee Ochoa and drummer Donald DJ Johnson are the band known as Khruangbin.

Even though their shows sell out globally like they did here in Vermont this summer, even they can't quite put a label on this moody genre they've called carved out.

MARK SPEER, Khruangbin: People still ask me, like, hey, so, oh, you're in a man.

What genre do you play?

I don't know.

WILLIAM BRANGHAM (voice-over): Whatever it's called, it has taken Krungman to great heights.

They've had hit collaborations with fellow Texan Leon Bridges and another with Sir Paul McCartney, those trademark black wigs that Mark and Laura wear.

They were initially put on as a lark before their first ever show, but they now offer an easy mask of anonymity.

Their records have earned them critical acclaim for their undefinable brew of rock, funk and psychedelia.

But even 15 years on, the band members say the process of crafting that sound is still evolving.

MARK SPEER: Earlier in our career, yes, we had a very specific way of making songs, but I feel like that's shifted over the years.

And I couldn't tell you exactly how we do it anymore because every time we go into it's different.

LAURA LEE OCHOA, Khruangbin: Yeah, they're just like puzzle pieces.

Almost like arranging furniture in a room.

You like, you don't know where anything's gonna go and then you find one thing that works and you're like, this is where this table's going to go.

MARK SPEER: And then you paint and it's like, oh crap.

Now I have to rethink the whole.

DONALD JOHNSON, Khruangbin: I mean we have a saying.

The song will tell you what it wants.

MARK SPEER: Yes.

And that's absolutely true.

But it almost takes a minute for the song to be like, put this drink down.

Oh no.

Yeah.

WILLIAM BRANGHAM: Do you really think I know we're talking metaphorically here, but do you really think of it as another organic entity that you guys are interacting with?

LAURA LEE OCHOA: The song?

WILLIAM BRANGHAM: Yeah.

LAURA LEE OCHOA: Oh yeah.

MARK SPEER: Yeah, Big time.

LAURA LEE OCHOA: Oh yeah.

MARK SPEER: When you're in love with someone, like really in love with someone, that's what this is.

When the song is there, it's not just three of us, you know, it's the whole thing.

WILLIAM BRANGHAM (voice-over): Khruangbin's success has ushered in a wave of other bands seeking to capitalize on this style.

Like Glass Beams, Arc Du Soleil and Yuuf, each offering their own take on this moody guitar driven genre.

Though Khruangbin is known for their musicality, there's also that pretty unusual name.

It's a Thai word that sort of means airplane.

And it is a tough one for even diehard fans to pronounce.

WOMAN: I was calling it like Kronga B Carabin.

MAN: Kurring bing.

MAN: Carbin.

Krabin.

MAN: Carbin.

Karabin.

WOMAN: Crabin.

MAN: I went on Google so many times for the pronounce WOMAN: Khruangbin.

MAN: Karagbin.

MAN: I think I'm saying it right.

Karangabing.

Is that right?

Karangabin.

WILLIAM BRANGHAM: What's the name of this band again?

WOMAN: Khruangbin.

WILLIAM BRANGHAM: You got it.

Given your guys success, did you ever think maybe we should name our band a more pronounceable word?

MARK SPEER: Well, we can't change it now.

LAURA LEE OCHOA: We wanted the website domain to not be taken.

MARK SPEER: Yeah.

WILLIAM BRANGHAM: What was the genesis of it?

LAURA LEE OCHOA: Part of it.

MARK SPEER: You can't call your band something like, you know, the shoes.

I mean they're great too.

But if you start like Googling the shoes, you're going to get a bunch of shoes.

You know, type in the first four letters of Our band name.

You're going to get us and Khrushchev.

LAURA LEE OCHOA: Yeah, that's it.

MARK SPEER: And he hasn't put out a record in years, so we're good.

WILLIAM BRANGHAM: Bombed.

WILLIAM BRANGHAM (voice-over): Even though they do occasionally layer vocals into their songs, almost always sung together, Khruangbin's essential sound is a trio of instrumentalists.

WILLIAM BRANGHAM: Do you think that there's something distinct about listening to just instrumental music that resonates with people differently than music that is more filled with identifiable lyrics and words and sounds?

LAURA LEE OCHOA: It's like the international language.

I mean, I think there's that part of it.

DONALD JOHNSON: That's something that we discovered early on when we were traveling throughout different countries that spoke different languages that we didn't speak.

We could just get on stage and play.

And it still works.

MARK SPEER: It allows the listener to create their own environment.

Doesn't tell you what you're supposed to feel or where you're supposed to be.

LAURA LEE OCHOA: I think it's also when there's not the human touchstone of a voice, I think it's slightly more challenging, but I think it's a challenge that people enjoy.

They have to get over that initial hump of being like, okay, I don't speak this language.

I don't know anyone at this party.

It makes you have to, like, intentionally listen and connect, and I think that can be really moving.

WILLIAM BRANGHAM (voice-over): Sometimes, though, their fans can't help but sing along, even if the words aren't there.

DONALD JOHNSON: This beautiful moment that we had once in Columbus, Ohio, early on, were playing Derncalle, and the entire room started singing Mark's guitar melody.

WILLIAM BRANGHAM: Wow.

DONALD JOHNSON: Didn't have words.

It was just da, da at the top of their lungs.

MARK SPEER: They were going off too.

DONALD JOHNSON: It was amazing.

No words, just people singing along with the melody.

And that's all you needed.

WILLIAM BRANGHAM (voice-over): For those other fans wanting to sing along with Khruangbin's tour, the band will be back in the U.S. later this month.

For PBS News Weekend, I'm William Brangham.