How can one human voice make such different sounds – and still be the same voice? The answer lies within your voice box, and how it can affect your vocal cords differently by arranging itself in certain ways.
We’re going to explore and explain the main muscles inside our voice boxes and how they work together in different ways to change the way our voices sound. We’ll also demystify some of the trickier terms like ‘modal register’, ‘thyroarytenoid muscle’, and even ‘laryngeal vibratory mechanisms’.
But before we get to that…
What are vocal cords?
Your vocal cords are two folds of tissue that stretch across your larynx (or ‘voice box’).
When you breathe, your vocal cords move further apart to let more air through, and when you swallow, your vocal cords move closer together to stop food from falling down into your lungs. When you sing, your vocal cords move between these two extremes, still moving quite close together to only let some of your air out.
Here’s what they look like from above open, then closed:
Vocal cords are sometimes called ‘vocal folds’ because, although in many ways, they do behave like strings on an instrument in the way that they tighten and loosen, they are not plucked or struck in any way.
Instead, their edges vibrate together as you push air through them, which is like the squeak that’s made when you let air out of a balloon. These vibrations then resonate in various parts of your body, with your chest at the bottom and your sinuses at the top.
Male vocal cords are longer (1.75cm – 2.5cm), which is why male voices are lower, and female vocal cords are shorter (1.25cm – 1.75cm), which is why female voices are higher. For both voice types, the voice becomes lower as the vocal cords shorten and higher when the vocal cords lengthen.
The easiest way to understand how these factors affect the rate at which your vocal cords vibrate, and therefore the pitch of the sound they produce, is to apply them to either a guitar string or, if you don’t have a guitar to hand, a rubber band.
First of all, you can immediately hear the difference between the low sound of a larger, thicker rubber band being twanged and the sound of a smaller, thinner rubber band, just as you can immediately hear the difference between the high E string and the low E string being plucked on a guitar. This is why a male chest voice will often sound lower than a female chest voice.
Second of all, you can easily hear the pitch of the twanged note rise when you stretch a rubber band and fall when you slacken it, just as you can hear the pitch of the plucked note rise when you tighten a guitar string and fall when you loosen it. Your vocal cords stretch and slacken in the same way when you move from one vocal register into the next.
What is a vocal register?
Simply put, a vocal register is a range of notes that you can sing with the same tonal quality. When the tone of your voice changes, that means your voice is moving into the next register.
In terms of which notes you can sing at either end of each register, there is some overlap – it’s almost like when you have to change gears when you’re driving a car (a manual car, that is!). The top speed that a lower gear can reach overlaps with the bottom speed that a higher gear can reach, and to transition smoothly from one to the next, you just need to get used to making that change at the right time.
Or, to bring back our guitar string analogy, think about how you can produce the same note on different strings. You can play a G3, for example, in 4 different positions on a guitar in standard tuning:
- Fret 15 on the low E string
- Fret 10 on the A string
- Fret 5 on the D string
- Fret 0 on the G string
Even though technically, these all have the same note value, you can hear the difference between a G3 played on the guitar’s low E string, and a G3 played on its G string. The low E string sounds duller, with a more bassy tone, whereas the G string sounds brighter, with a more trebly tone. Your voice differs in this same way as you sing in each vocal register.
Traditionally, the four vocal registers, from lowest to highest, are:
- Vocal fry register
- Modal register, or chest register
- Falsetto register, or head register
- Whistle register
The main vocal registers that singers use are chest register, for lower singing, and head register, for higher singing.
Some singers use the vocal fry register when they want to sing even lower, and some singers use the whistle register when they want to sing even higher.
What are ‘chest voice’ and ‘head voice’?
It’s important to note that the terms ‘chest voice’ and ‘head voice’ have been described as such for hundreds of years – long before we had the technology to actually observe and examine how the human body produces these different sounds.
It’s easy to understand why these names were chosen for these voice types when you produce them yourself. When you sing in each of these voices, you can feel your voice resonating in the part of your body that the voice is named after. Let’s try it out!
Sing a lower note
When you sing using your ‘chest voice’, you’re singing in the same range you use for speech. This is the go-to range for most people to sing in, and should feel easy and natural without requiring too much thought or effort.
Try humming a comfortable, continuous note – not too high, not too low – and place a hand on your chest to feel your voice vibrating in there. Imagine your voice is on a slide whistle, and see if you can follow the vibrations going up and down in your chest as you gradually raise and lower the pitch of your hum.
Sing a higher note
Now that we know where we can feel the vibrations of our chest voice, it’s time to take things up a notch. A good way to find where your chest voice ends and your head voice begins is by starting in chest voice, then sliding the pitch up higher and higher until you feel it begin to strain slightly – you will probably also hear your voice ‘crack’ or ‘break’.
This strain or break is an indicator that you need to move from your chest voice, which is also called the ‘modal register’, into the next vocal register. You’ll know you’re singing in your head voice because you can feel your voice vibrating in your head, and not so much in your chest – and once you know how the vibrations of the two different voices feel, you can ‘aim’ lower notes toward your chest and higher notes towards your head to help get you in the ballpark.
We all have a unique voice and a unique vocal range, but if you have a male singing voice, you might start to notice a strain in your throat between an E4 and G4 above middle C if you’re still using your chest voice, and if you have a female singing voice, you might notice this strain between an E5 and G5. If you have a piano keyboard or an app that will let you find these notes, see if you can match these notes while ‘aiming’ your voice towards your head.
‘Chest register’ and ‘head register’, or ‘chest voice’ and ‘head voice’, are still used by some music teachers and vocal coaches to describe the different vocal registers because this way of matching a way of singing with where you can feel it is easier for new singers to understand.
However, these terms can be misleading, because all the sound you make with your voice is made in your larynx, which is located in your throat, rather than in your chest or head. When you switch gears from one register to the next, it’s your larynx doing the majority of the work – let’s find out how.
How does my larynx change the pitch of my voice?
Apart from the difference in pitch that you can hear, a major difference between your chest register and your head register is that they each use different groups of muscles inside your larynx, which affect your vocal cords in different ways to change your voice’s pitch.
Watch this animation to see these muscles in action and to hear the results:
These muscles are named after the parts of your larynx that they connect to – in this case, we’re mainly concerned with how 3 of main cartilages are joined together:
- your thyroid cartilage, the front part which you can see part of forming your Adam’s Apple
- your cricoid cartilage, a ring found beneath your thyroid and above your trachea (or windpipe)
- your arytenoid cartilages, which are a pair of pyramid-shaped cartilages at the back of your larynx that sit on top of your cricoid cartilage
There are other parts of the larynx too which help us to do other things, but let’s look at the muscles that connect and move around these 3 cartilages:
Thyroarytenoid (TA) muscles
Joining your thyroid and arytenoids together are the thyroarytenoid muscles (or ‘TA’ muscles, sometimes called ‘shorterners’). The TA muscles are the innermost part of your vocal cords, with one TA muscle running the full length of each vocal cord from your thyroid to each arytenoid.
Your TA muscles’ job is to pull your arytenoids at the back of your larynx closer together with your thyroid at the front.
As they contract and narrow the gap between your arytenoids and thyroid, your vocal cords slacken and bunch up, becoming shorter, thicker, and looser. Since your vocal cords are shorter and under less tension at this stage, they vibrate at a lower frequency when you push air through them, which produces lower-pitched notes.
Also, since they’re thicker, the area of contact between your two vocal cords is larger – both the outer layers, or ‘cover’, and the inner layers (including your TA muscles), or ‘body’, of your vocal cords are brought together. Because more muscle is working together at this stage, a more powerful vibration is caused when you push air through – which is why, especially if you’re a beginner vocalist, your chest voice sounds so much stronger.
Cricothyroid (CT) muscles
Joining your cricoid and thyroid together are the cricothyroid muscles (or ‘CT’ muscles, also called ‘stretchers’). The job of these muscles is to stretch and thin out your vocal cords.
As the TA muscles relax, the pitch of your voice increases, but at a certain point a separate pair of muscles take over – the CT muscles – which pull your thyroid cartilage forwards and downwards, away from your arytenoids, stretching your vocal cords until they’re thinner, longer, and tighter. Since your vocal cords are thin and under more tension, they vibrate at a higher frequency when you push air through them, which produces higher-pitched notes.
Also, since the vocal cords are stretched out more thinly, the area of contact between them is smaller – in fact, only the ‘cover’ vibrates, whereas the ‘body’ does not. Because there is less muscle involved at this stage, the vibration caused when you push air through is less powerful – that is, of course, until you start developing it with practice.
Laryngeal Vibratory Mechanisms
As a result of these discoveries, many voice coaches and singing tutors are moving away from older terms like ‘chest voice’ and ‘head voice’ in favour of a new naming system which describes what the larynx and the vocal cords are doing in each vocal register. Each of these ‘Laryngeal Vibratory Mechanisms’ is given a letter M, then numbered 0-3:
| Laryngeal Vibratory Mechanism | Vocal register | Laryngeal muscles in use | Vocal cord behaviour | Vocal range |
| M0 | vocal fry | TA in full use, CT not in use | Body and cover both fully slack and vibrating slowly | Male: D#2 and belowFemale: E3 and below |
| M1 | modal/chest | TA dominant | Body and cover both thick and vibrating | Male: D#2 – G4Female: D3 – G#4 |
| M2 | falsetto/head | CT dominant | Body and cover both thin, body stops vibrating | Male: F3 – F5Female: G#3 – C6 |
| M3 | whistle | CT in full use, TA not in use | Body and cover both fully stretched, only cover vibrating | Male: E5 and aboveFemale: A5 and above |
So we naturally speak and sing in the M1 register, then move down into M0 when our voice bottoms out into vocal fry, move up into M2 when we switch into our head register – and up further still into M3 for the whistle register.
When you sing in M1, both the body and cover of each of your vocal cords are vibrating together, but as you move down into M0, they vibrate together so slowly that they sound in danger of stopping making any noise.
When you sing in M2 and move up into M3, only the covers are vibrating together, but when you sing in falsetto, your vocal cords disconnect, allowing you to make that breathy sound – read more about the difference between head voice and falsetto in our article.
Is mix voice a register too?
You may have heard your teacher use the terms ‘middle voice’, ‘mixed voice’ or ‘blended voice’.
There is technically no middle register in the laryngeal sense, because there is no point where the TA muscles and the CT muscles can both be dominant.
Your mix voice is more of a balance between registers which you can achieve when singing in the range at the top of M1 and the bottom of M2, just before either set of muscles takes full control of your vocal cords.
However, the mix voice is considered by many vocalists and vocal coaches to be the ‘holy grail’ of voices – you have the power of the chest voice, with the upward mobility of the head voice. What’s not to love?
How can I find my mix voice?
Finding your mixed voice is really all about knowing when to change which register you’re using – and trying to make that change without any breaks in your voice. The musical term for the point where you switch registers is ‘passagio’, meaning ‘passage’.
As we saw earlier, the range of each vocal register overlaps with the range of the next vocal register. This gives you an opportunity to change to the next register before you reach the limit of the register you’re currently in.
Watch this video to see where the registers overlap for males voices and female voices:
Learning how and when to use your mix voice is useful, because otherwise you might try to change registers too suddenly, and make some unwanted noises.
If you bring your chest voice up too high, you might naturally try to yell to hit the high note you’re aiming for, and produce a harsh sound that could strain your vocal cords.
If you bring your head voice down too low, you won’t be able to sing with enough power to make your voice resonate properly at the lower pitch.
So, to overcome these breaks, you need to prepare your voice as you approach the change from one register to the next. The way to achieve this is to change amount of intensity you’d approach the rest of that register with:
- When you’re in M1 and are approaching M2, you need to sing with less intensity.
- When you’re in M2 and are approaching M1, you need to sing with more intensity.
Your voice in a more intense M2 sounds very similar to your voice in a less intense M1, so you’re effectively disguising the fact that you’ve changed registers.
The range of notes that M1 and M2 share spans from around B3 to around F4 – this range sits comfortably in both M1 and M2 for male voices and female voices.
This means that, whenever you’re singing a song that’s mostly in the lower M1, but when you reach a part that’s going to work its way up to a higher note outside M1’s range (like an A4), you’ll need to make the change to M2 at an earlier, lower pitch (like an E4), so you’ll already be using the right register to reach your A4.
Likewise, if you’re singing a song in the higher M2 register, but reach a part that’s going to dip down to a lower note outside M2’s range (like a G3), you’ll need to make the change to M1 at an earlier, higher pitch (like C4).
The same goes for switching all the way down to M0 and all the way up to M3 – make the change earlier (but not too early!), and you’ll find that you can move more easily and comfortably into the next vocal register.