Miley Cyrus couldn't control her excitement. For once, she was the fan losing her chill, all because the "coolest person" she knew was about to make her debut at The Forum.

"Her voice — oh my god — her voice is amazing," Cyrus gushed onstage, waving a giant homemade sign that was equally gushing.

Was this an alternate universe? No, the Disney Channel alum happened to be introducing her little sister, Noah Cyrus, at the iHeartRadio Music Awards a couple weeks ago. You'll be hearing a lot more about her in the coming months.

Fans probably first met Noah in that adorable Hannah Montana episode about a meowing cat sweater — the first of several cameos she made in her big sister's beloved TV series before it wrapped in 2011. But fast-forward to today, and the youngest Cyrus is not so little anymore.

Now 17, Noah kicked off her music career with "Make Me (Cry)," a collaboration with R&B singer-songwriter Labrinth. The emotional lyrics scrutinize a troubled relationship, while the music video shows Noah serenading her sleeping lover in bed — an effective visual to let your audience know you're all grown-up.

The title of her upcoming debut album is just as mature: NC-17, inspired by the MPAA's rating for movies that are forbidden to anyone 17 and under. When I recently spoke to Noah on the phone, she revealed the name is also a nod to her initials, age, and 2017 in general.

Judging by the past two months alone, it's shaping up to be a spectacular year for Noah. She and Labrinth had already performed for James Corden and Jimmy Fallon before they sang their guts out at an awards show on live TV.

"Falling in front of an audience, that's like my biggest fear," she confessed when I asked if she was nervous. Fortunately, gravity was on her side at iHeartRadio. The duo crushed their duet as the Cyruses cheered them on from the crowd. Music is practically in the family's blood, from Billy Ray's country classics to Miley's chart-topping hits to Trace Cyrus's pop-rock band Metro Station. Watching their careers over the years taught Noah how to approach her own.

“You should do the sound that you want and not what others want," she recalled learning. "I think that if you love yourself and the way that you’re doing the music, then you’re doing something right, and that’s something that they’ve always done."

NC-17 isn't tied to one specific sound, and Noah teased the "many different stories" the album will tell. "Almost Famous," for example, is a beautifully honest breakup song. Lyrics like "you were the right face at the wrong time" are painfully spot-on.

"I broke up with my boyfriend and I was like, 'Oh shit, I really messed up,'" Noah revealed. Like many singer-songwriters, her real-life experiences inspire her art. She's been writing since age 14, but got serious about NC-17 after scoring a record deal and feeling especially inspired by Ben Howard's I Forget Where We Were. Her album's not finished yet, so the release date remains one giant question mark: "I just want to get it to the point where I’m like, 'All right, this is like, my dream album. It's finally there.'"

In the meantime, Noah's small handful of original releases — plus some awesome covers — will have to do. For her latest, she teamed up with Marshmello, a DJ-producer who made serious waves in the EDM world last year. He remixed "Make Me (Cry)," then Noah hopped on the vocals for his "Chasing Colors."

It's worth nothing that her famous surname does come with some strings attached. For one, Noah grew up in the spotlight — her "normal," she said — which trained her to keep certain parts of her life private. Second, her voice is often likened to Miley's — we noted their similarities when "Make Me (Cry)" came out — but Noah has previously said she's not bothered by the comparisons.

Miley seems unfazed as well. As the proud big sister, she continued her iHeartRadio introduction by raving about how "relatable" Noah's music is. "She knows exactly what I'm going through; she is who she is as an artist," Miley announced to millions of viewers. "She's who I wanna be when I grow up, and that's saying a lot, because she's a lot younger than me."

Clearly, there's always room for one more Cyrus.