Here is a blog you can refer to whenever you are unsure about what someone is doing, or what you are doing with your own voice on a particular song, and whether or not that's something that you should be, or should not be doing. This is LONG, but important. And this blog certainly is not intended to include ALL the answers when it comes to vocal technique, but is merely a step one listening guide.
First, please understand this...
Recent research in voice science is showing that it is risky for young singers (under 18-21) to belt regularly. The definition of belt is, taking pure chest register up higher than the FIRST fence/passagio (E, just above middle C). So, when I work with younger students (females, in particular) we work to lighten the middle/mix a bit. Not permanently (you won't lose the ability to belt), but to give you more artistic, aesthetic, healthy choices for middle and high notes.
For this critical, analytical listening, please use your best quality sound system, headphones or ear buds. If you don't have a high quality set of headphones, you should ask for one for your birthday or Christmas, if your family celebrates those occasions with gifts. It's important to have high quality listening equipment because of the level of clarity required to hear the subtle differences I'm talking about here.
Example One, Whitney Houston's debut album: https://youtu.be/OtssG0CYv48?list=PL9Nuk30zTsfv3bJIq0tKXm-7nVi3KC0Zv
Some belty stuff in the first track, but not much. The second song is very light and mixy and not shouty/belty at all. Always ask yourself, "how loudly does it sound like she is singing?" Adele = LOUD. Tori Kelly = not as loud. Tori and Ariana Grande sing in the same range and are both higher than Adele by quite a bit. Adele is pretty heavy/chesty most or all of the time, except when she flips to head register. Notice how Arianna's and Tori's voices are thinner and lighter up high, but still sound chesty. That smaller sound is easier to take up high than the heavy belt that Adele uses.
Example Two, Adele, Rolling in the Deep: https://youtu.be/rYEDA3JcQqw
I know you've heard it a hundred times (or more) but really listen to her voice. Remember the second biggest influence on which register we sing in is volume, and the third biggest is the vowel. Notice almost every ee and ooh she sings flips to head register. Especially on "rolling in the deeeeeeeep." If her mix was lighter, she would be able to stay out of head register there. Whitney became THIS in the end of her career. See below...
Example Three, Whitney, I Will Always Love You: https://youtu.be/3JWTaaS7LdU
Still a fantastic performance, but by this point in her career her mix became heavier (reasons why will be discussed later) and as a result, she became a "flipper." She flips to head a LOT in this song. But, it is often on the ooh vowel, which loves head register.
You would hear the same types of things in Christina Aguilerra's and Mariah Carey's voices if you compared their debut albums (age 19) to their later albums.
Example Four, Tori Kelly, Paper Hearts: https://youtu.be/NO8zDm437Ls
Lots of light, mixy stuff here and no belting. Her head register is a bit breathy but that may be an artistic choice. She also utilizes a few of the "squeaky" sounds that voice teachers cringe when they hear, but like most extreme techniques (like distortion/rasp) if used sparingly, the voice should be able to handle it.
Example Five, Ariana Grande, Emotions (Mariah Carey cover): https://youtu.be/UjzENV7rhhI
Much light mixy singing here. In fact, her mix is a bit headier than most, and the lack of clarity in her words is the result of that. Chest register is bright, head register is not. She doesn't have nearly as bright a tone as Tori Kelly, so we can conclude that her mix is headier. Also some breathiness, but I believe that is a choice.
So, lightening things in the middle is KEY to being able to sing powerfully for many years! Please don't spend more then a few minutes per day in your super high, loud belty voice. Your future voice is depending on you to make good decisions NOW!
All of these ladies had super heavy touring schedules. Along with that comes meet and greets before and after the show, speaking to fans in loud environments (the worst!), morning radio and TV interviews, etc. In short, they are constantly booked to do (speak or sing) something with their voices and that can become very stressful. Add to that, the much publicized lifestyle choices that these three ladies made in their 20s and 30s (drugs and alcohol) and it's a recipe for vocal trouble.
As I stated in the introduction, this blog is only meant to be a conversation starter and by no means contains all the answers to what teenage girls should or should not sing. I am available for consultations at firstname.lastname@example.org Feel free to contact me if you are interested in either Skype or in person voice lessons.