The miracle of rap music is that it metabolizes wild-styles faster than any other American art form — which means outsiders can bum-rush the center with a quickness. Remember when Lil Yachty dropped his debut mixtape last spring? And it sounded like sleepy braggadocio rendered in Pixar rainbows? And it was radiant enough to freak the squares, mobilize the scolds and lure the rest of us into a beautiful hallucination that 2016 wasn’t all that bad? Here’s the weird part: Fourteen months later, Lil Yachty doesn’t sound like a brat, or a heretic, or even that much of a freak. Instead, today’s rap music sounds a little more like him.

In a mischievous stroke of savvy, the kid accelerated his ascent by repeatedly goading the old guard. Last year, when he bragged about his inability to name five Notorious B.I.G. songs, purists instantly went bananas flambé. And while Yachty was obviously trolling his elders for attention, he was also reminding us that history is heavy, and that young visionaries have every right to brush it off their shoulders when they’re trying to build something new. That’s the image Yachty has upheld ever since. He’s a seize-the-day optimist preaching positivity and possibility. If capitalism is your religion, you might call it his “brand.”

But if you listen closely to the 19-year-old’s new album, “Teenage Emotions,” you’ll be reminded that Yachty is a sound more than an image. He wouldn’t be here if not for his strange, yawning delivery — a loosey-goosey approach where vowels get stuck on the roof of his mouth, then spill onto the rhythm, messy and sweet. Old heads balk at his singsong rhymes, his cheery idealism and his Atomic Fireball hairdo, but it’s clearly the sound of Yachty’s voice alone that has rankled the establishment most.

Now he’s stretching out, expanding what that voice can do. The most saturated line on “Teenage Emotions” is casually tucked into the center of “Say My Name,” a colorful rags-to-riches tale set to a barely-there beat. “My brother used to sleep in a Hyundai,” Yachty yelps. “Now he spend about a hundred Gs on a fun day — Wow!”

There’s something deeply satisfying about that trapezoidal rhyme — “Hyundai” and “fun day,” “now” and “wow” — but even more beguiling is how Yachty’s Auto-tuned mewl makes him sound astonished, grateful, overwhelmed, on the verge of tears, laughter or both. He packs a spectrum of emotions into those 24 syllables, and you don’t have to be a teenager to hear them all blurring together like watercolor.

As for his darker feelings, he telegraphs them deeper in the track list. “No More” is a fatiguing slog through his disinterest in fame, while “Made of Glass,” about an unrequited love, comes garnished with a lovelorn sigh: “You don’t even see me.” Here, things start to feel disingenuous. Surely, Yachty contains multitudes, but it’s hard to imagine someone who exudes this much life-force ever feeling bored or invisible.

Still, we should feel encouraged by a pouty Yachty — at least in theory. If he was shrewd enough to construct a persona this magnetic, he’s smart enough to know that he’ll soon have to erase it and start over. He may have bent rap in his direction, but he can’t slow it down. If he doesn’t invent tomorrow’s wild-style someone else will.