When vocal coach Eric Vetro was introduced to a then 13-year-old actress named Ariana Grande, his first thought was “superstar.” “The voice, the personality, the charisma, it was all there… Anything you see of her now really was there already,” he tells Billboard. Since that fateful day, Vetro has become “like family” to the Grandes, spending several holidays together and honing young Grande’s voice to meet every career milestone that lay ahead — from recording her breakout hit “Dangerous Woman” to transforming into Glinda for Wicked.

Vetro has become the go-to voice maestro for just about everyone in the entertainment business, ranging from ROSÉ to Rosalía, and he’s become especially adept at teaching actors how to prepare for musical biopics. He’s helped Jacob Elordi and Austin Butler prepare to play Elvis, Timothée Chalamet to play Bob Dylan, Angelina Jolie to portray Maria Callas, Jeremy Allen White to do Bruce Springsteen and more. And, to top it off, he’s also been a guide for Broadway stars like Lea Michelle and Bette Midler.

On this week’s episode of Billboard On the Record, Vetro joins the podcast to explain this little-explored — but crucial — role in the music industry, helping stars maintain their voices despite often stressful, demanding schedules.

Check out the full episode of On the Record below on YouTube, or check it out on other podcast platforms here. Read a condensed and edited portion of the conversation below.

Let’s start off with an easy question — Can anyone sing?

Eric Vetro: Absolutely not. And I know that everyone probably wants to hear, yes, but it’s just not the way it is. I mean, I always say to everyone, I can make you sound better. I can’t guarantee you’re going to be the greatest singer ever, or that you’re even going to sound amazing, but I can guarantee you’ll get better. You either have the potential in your vocal cords or you don’t. But it’s not just vocal cords — it’s your ear, it’s your sense of pitch, it’s what you do. Can you convey emotions in the music? But it really comes down basically to the vocal cords and the sense of pitch, and if you don’t have those things, I’m sorry.

I think there’s this notion that singing pop music is not difficult, especially in comparison to other styles like classical or jazz or Broadway. But I do imagine that even though a talented singer may be great at classical, for example, it doesn’t mean they can walk in the next day and do pop. What do you think? Can many vocalists easily switch between genres?

I don’t think a lot of people can do it easily, that’s for sure. But some people have such great vocal cords. [I work with] Rosalía [and] Ariana Grande. Those girls can do it because their vocals are basically capable of doing anything. They have very, very wide ranges, so if they don’t sing very high, they can sing very low, and they have a really great mastery over their own voice. So, for people like that, yes. They can switch in between, but most people can’t.

Most of the pop singers around could not turn around and do a Broadway show, or certainly do an opera easily, or make an operatic recording. Even Ariana, with the great voice she has, actually worked quite diligently to sound like the voice that she wanted Glinda to have — that legit Broadway soprano voice. She worked very hard on that, even though she already could imitate anybody under the sun.

You’ve worked on a lot of musical adaptations and biopics for the big screen, including Wicked with Ariana. How do you approach teaching someone to sing like a character whose identity is already set — like a real person or a famous character?

I never want anyone to sound like an imitation. It’s always the goal of getting the essence of that performer, what makes them special, what makes their voice unique, what makes it identifiable. [Ariana] was very, very determined not to sound like an imitation of anyone and to be her own Glinda.

What I do is, I say, who are the influences of this person [you’re playing]? So, with Austin Butler, we listened to a lot of people that Elvis liked. Or the same thing with Timothée Chalamet — who was Bob Dylan influenced by? Who did he listen to?… Even if it’s not identical — don’t worry, you don’t want it to be. They could hire an Elvis impersonator, and the impersonator may sound like Elvis, but it’s not going to capture the magic. That’s what you want to do. You want to capture the magic of that person.

You worked on the Bob Dylan biopic, and I think Bob Dylan is a perfect example of an artist who is known for having a very distinctive voice, but as he’s aged, his voice has changed completely. Is it common to have a singing voice evolve that much with age? I also know he’s smoked some cigarettes and drank some whiskey in his day, though…

The aging process obviously affects us in every possible way — our lung capacity, our stamina, our memory, everything. However, how you take care of yourself is what makes the real difference. So one would be all those things you just mentioned: smoking, drinking, any kind of drug abuse, all of that is going to affect your body and therefore affect your voice. But also, some people train better than others. Some warm up for every show, some don’t, and that can really cause a lot of strain and deterioration on the voice, because if you’re going out there cold and then singing really strongly, and not singing for a few days, and then hit it again that can really start affecting your voice. A lot of times when I hear someone, I’ll know right away if they’ve been maintaining their voice by doing vocal warmups. Following the acid reflux diet — what you eat and what you drink really affects your voice. I always say that’s a really important part of it too, and you can hear that some people’s raspy voice comes from what they’ve been eating and drinking.

Do you find that people who are primarily actors approach singing differently than someone who considers themselves to be a recording artist?

Yes, but a lot of it is because they haven’t done it before, and so they don’t really have a history or a background or a lot of experience with singing. So yes, they would be considered much different. That’s why, whenever I work with anybody, given the amount of time I have — even if it’s, let’s say, one month — I’ll spend the first week just working with them on their voice, helping them to understand their voice, how to best use it, how to support their voice, how to train, all of that. That’s just so they have an understanding of their own voice. Then we start trying to work on the voice of whoever they’re going to portray because I think that’s really important. If you’re working with someone who’s sung all their life, like an artist, then you don’t have to do that.

Do you typically take on clients that have a specific thing that they’re working toward or is it clients that are indefinitely on your roster?

It’s all over the map. A lot of the younger ones, like Ariana, Sabrina [Carpenter], Rosalía, Shawn Mendes — all these young students I started with — a big part of it is trying to help them learn how to maintain their voice. People don’t realize how much stress and strain there is on the human voice for these people. I think most audience members just think, oh, they sing at night, either on stage for an hour and a half or two hours somewhere, or they do a couple songs on an evening talk show. They don’t realize they might have been up at 5 [a.m.] for Good Morning America or one of those shows, and have to get there really early — like 5, 5:30, 6 in the morning, do camera blocking, do a soundcheck, get into hair and makeup, then do the show, then maybe a pop-up meet-and-greet, then an interview, then soundcheck at the venue, then getting ready for the show, all of that.

When you’re young, it’s hard because you might be born with the ability to sound good and sing well, but you’re not born with the ability or the knowledge or the technique of how to maintain your voice when you’re doing all of that.

In Rosalía’s latest album LUX, she sings in 13 languages. How did you help her prepare to sing through all those languages in one project?

She was already, I think, pretty skillful at doing different languages. And she will always make jokes about her English not being perfect, but it’s great. You can understand everything she’s saying. She has a really, really great ear for language. I think when you have that gift, then doing 13 different languages — it’s not easy, for sure, not easy. She worked really hard on it, but she did have an aptitude to do it, and she also was one of the hardest-working people I’ve ever known in my life.

I just imagine some of the languages, like German, for example, that are really consonant-heavy might be a tough adjustment.

She worked so hard. I worked with her for quite a long time, and there were times when we would go every day for months. I would FaceTime her wherever she was in the world, different countries, different places, and we worked a lot on vocal placement, healthy vocal placement, so that even if she was going to sing a language that might be considered a little bit more guttural, she still understood where she had to place her voice to keep healthy and to sound its best.

Another one of your clients, Charlie Puth, just performed the national anthem at the Super Bowl. Some say that the national anthem is one of the hardest songs that a singer can sing. Do you feel that that’s accurate?

It is a difficult song. It does have a wide range. I think what makes it more difficult than people realize is a lot of the held notes. There’s a lot of held notes. Someone who’s been on Broadway or grown up with that type of music, holding long notes is all part of it, but most pop songs don’t have a lot of long held notes or notes that might have a lot of vibrato in them. In The Star-Spangled Banner, the highest notes are held for quite a long time, and that partly makes it difficult.

Then, of course, depending on the venue and the skill of the engineer who’s working with your in-ears, that can be very challenging. Sometimes it’s hard to hear yourself correctly, because there’s a lot of echo and reverb. It’s a huge stage, and that can be daunting, even for someone who’s performed their whole life. That is a huge crowd, and that crowd is not there for you — they’re there for the game. People say, well, they’ve sung to stadiums before and arenas, and I go, yeah, but for audiences who are there for them, who came to watch them because they love them — not because they were there for a baseball game or a football game. These aren’t your crowd, so you’re trying to win over that crowd.