Speech and singing
Speech and singing
The human voice is created in the larynx, where the vocal cords, or more correctly, the vocal folds are located. Between the vocal folds is a narrow slit called the glottis. When you breathe in normally, the vocal folds are relaxed, and the air passes through the glottis. But when you tense the muscles in your throat, the glottis gets narrower. Then the air has to be pressed through, and it starts to vibrate.
The tighter the vocal folds are, the faster they will vibrate. And the faster the vibration, the higher the pitch of the tone produced! Men usually have larger larynges and longer vocal folds than women and children. That's why their voices are deeper. When a man uses his normal voice, his vocal folds vibrate with about 100 oscillations per second.
Women's vocal folds vibrate with about 200 oscillations per second. When you sing, you form different tones, by tightening and relaxing your vocal folds, to increase or decrease the pitch. But it's not only your vocal folds that determine the sound that's heard. When the vibrations come up from the vocal folds in your throat, your mouth, tongue, and lips also shape the sound. By moving your mouth and tongue, you can create different sounds, from the same vibrations.
So there are two things determining how your voice sounds. One of them is how your vocal folds vibrate. That's what determines the pitch and amplitude of the sound. The other thing determining what your voice sounds like, is how the sound waves are shaped in your mouth, nose, and sinuses. This is where we create speech sounds, that enable us to talk.
And you can also create sounds without using the vocal folds. These are unvoiced sounds. They are created entirely inside your mouth, without the help of the vocal folds. Place a finger on your larynx, and try for yourself - you can feel which sounds come from the vocal folds' vibration. When you whisper, you also don't use your vocal folds.
Instead, an unvoiced hum is created, just behind the vocal folds, which you can then form different sounds with, by shaping your mouth and tongue. When we enter puberty the voice changes. It's sometimes called voice mutation or voice break. The voice change is caused by the larynx growing. It makes the vocal folds longer, and the voice deeper.
The larynx grows more in boys than in girls. That's why the voice change is more noticeable in boys. When we catch a bad cold, the vocal folds can get swollen. Then the voice gets hoarse and rough. If you have mucus in your sinuses, and a blocked nose, your voice is also affected.
It's almost like going from a cave -- ... to a room covered in soft pillows. You can do quite a lot to change your voice. You can alter the amplitude by increasing the pressure from your lungs. You can alter the pitch, by tensing your vocal folds -- You can use your mouth to make a funny voice.
But even if you alter your voice, it's always unique to you. There is no one else that sounds exactly like you do! This fact can be used to identify people, using voice recognition technology. Your voice is unique, and so is everyone else's!