How Mariah Carey and Ariana Grande hit those crazy high notes, according to science

It's been a couple of days, and a large part of the Internet is still losing its shit over a remix of Mariah Carey’s “Oh Santa!” featuring Jennifer Hudson and Ariana Grande, which dropped on YouTube on December 3. One snippet of the track, from Carey’s Apple TV+ Christmas special, floored us in particular (as in, some of us tweeted that we literally needed someone to help us off the floor) — Carey and Grande harmonizing their whistle tones.

As a health reporter who also happens to stan both pop stars, I couldn’t help but ponder the physiology of this elusive vocal register. How do Mariah Carey and Ariana Grande hit those whistle notes? I spoke with vocal experts to find out.

For those unfamiliar, the whistle register, as its name implies, "sounds like a whistle, a very high sound," explains Annette Philip, faculty in the voice department at Berklee College of Music. "The whistle register is the highest vocal register that can be created by the human voice." Growing up listening to Carey, I called it the “dolphin whistle” — the notes she hit were so high, I really wondered whether she could commune with dolphins. Besides Carey and Grande, Minnie Riperton, as well as singers from cultures around the world, have gilded their songs with whistle notes, according to Philip.

Before we delve into the details of what creates whistle notes, some background on human vocal registers: The chest and head registers are the most common, Philip says. Notes in the chest register are lower and resonate in the chest, where you can actually feel vibrations when you sing them. Meanwhile, notes in the head register are higher and resonate in the head. Some vocalists claim that when they sing in this register, they can feel the vibration in the back of their neck, says Laura Portune, a senior lecturer of voice in the School of Music at the Ohio State University. She teaches her students to "sing more in the center of the forehead" as they climb toward higher notes.

As you continue this ascent, “you extend the head voice even further and further, and that is where you eventually start to access your whistle register,” Philip says. Where, then, do you feel notes in this register vibrating in your body? Many report feeling it in their forehead, Philip notes, while others feel it coming out of the top of their head. Portune tells me she's experienced this. "I don’t feel it vibrating. It almost feels outside of your body,” she says, a dramatic description that seems only fitting for a sound that leaves us so shook.

Now let’s look at how your vocal cords — folds of tissue that sit in a region of your throat known as the larynx, Philip explains — produce these whistle tones. When your vocal cords vibrate, they create sound, not unlike when you pluck the strings of a guitar. That is, when they shorten and thicken, they vibrate slower to produce a low-pitched sound, and when they elongate and thin, they vibrate faster to produce a high-pitched sound. Elongating and thinning them even more — like you might do in the whistle register — causes them to vibrate faster still to produce an even higher-pitched sound. While they vibrate freely along their entire length in the chest and head register, only a short section of the vocal cords vibrate in the whistle register.

It's not just this vibration that produces the whistle sound, though. Air pressure matters, too, similar to when you blow into a literal whistle. Blowing softly might result in a sad, sighing sound, while blowing hard produces that characteristic, high-pitched brrrrrrrrrt.

But Portune says we're not entirely sure what the vocal cords are doing at this point, since when people hit the whistle register, a flap of tissue called the epiglottis covers the larynx, preventing specialized cameras from visualizing them. That said, the closed epiglottis may create a smaller space in the larynx, and smaller spaces resonate at higher frequencies — that’s why a violin produces a higher pitch than a cello, as an expert I previously interviewed for Vice explained.

Carey has credited her ability to “sing around” the nodules on her vocal cords for her impressive range. These nodules — calluses, essentially — form when the vocal cords repeatedly vibrate against each together, such as when you constantly sing in a high register, at a loud volume, or with incorrect technique, Philip says. She thinks Carey probably experimented with her voice from an early age, which might’ve led to these nodules, and learned proper training to avoid them later.

That doesn’t mean you should get them on purpose to broaden your range, since they can prevent your vocal cords from vibrating properly against each other, she notes. "Beyond a certain pitch, they just get air and not tone." Portune agrees. “It’s damaging and compensatory,” she says. “You have to be able to change something to sing through it.” That’s likely what Carey meant by “learning to sing around” her nodules.

Philip compares the whistle register to ballet. We typically walk using our entire foot, but ballet dancers are trained to spend most of their time on their toes. Likewise, we don’t usually speak in a whistle register, so accessing it does require training. And while it may seem magical, “in general, it is said if you really spend time on it and focus on it, almost anyone can get access to it.” Some may find it easier than others, though, and it can take years to learn to master it with the same control as Carey or Grande. (They’re superstars for a reason.)

If you want to emancipate your inner Mimi and unleash your whistle register, Philip recommends training with a vocal coach who has expertise in it to avoid injury. Take things slow, and listen to what your body says about whether this register feels natural and comfortable long-term. At the end of the day, you may decide it’s not all that important for you to develop, and that’s ok. Whistle notes may thrill us because we so rarely hear them in pop music, but that doesn't necessarily mean they're the pinnacle of vocal prowess.

“Ultimately, it’s not about the high note or the fast note. It’s about telling stories,” Philip says. Like any technique, the whistle register “is just another beautiful color to play with.”

She's right. While Carey and Grande’s soaring whistle tones dazzle me, so, too, do Hudson’s rich, brassy ones. Now excuse me while I marvel at all the vocal colors they play with in “Oh Santa!” and listen to it at least 50 more times.