Human voice

The human voice is the sound made by a human being using the vocal tract. This includes many things we do like talking, singing, laughing, crying, screaming, shouting, humming, and yelling. The main part that makes these sounds is the vocal folds, often called vocal cords, in our throats.

To make voice sounds, three main parts work together: the lungs, the larynx (or voice box), and the articulators. The lungs push air up to make the vocal folds vibrate, creating sound. The muscles in the larynx change the shape of the vocal folds to adjust the pitch and tone of the voice. Then, the articulators—like the tongue, palate, cheek, and lips—shape and fine-tune the sound as it comes out.

Our voice is very powerful. We can use it to show emotions such as anger, surprise, fear, happiness, or sadness. It can also tell others about our age and whether we are male or female. For singers, the voice becomes a musical instrument that helps create beautiful music.

Voice types and the folds (cords) themselves

Main articles: Vocal folds and Voice types

Men's and women's voices usually sound different because their vocal folds, also called vocal cords, are different sizes. Men's vocal folds are typically longer, between 17 mm and 25 mm, which makes their voices sound lower. Women's vocal folds are shorter, between 12.5 mm and 17.5 mm, so their voices usually sound higher.

These folds are located in the larynx, or voice box. They are attached at the back to the arytenoids cartilages and at the front to the thyroid cartilage. The inner edges of the folds can vibrate to create sound. Because of these size differences, men's and women's voices have different pitches and tones. Voices can also be grouped into different types, like bass, tenor, alto, and soprano, depending on their range and quality.

Voice modulation in spoken language

When we speak, most people can change how their voice sounds in a special way. The two biggest things we change are how high or low our voice sounds (called pitch) and how close together our voice parts (vocal folds) are.

Our bodies are made to change how close these voice parts are very quickly. This helps keep food from going into our lungs when we swallow. Even young children learn to change their voice this way when they start talking. They can tell the difference between sounds like "apa" and "aba" before they turn two, just by listening to adults around them.

Sometimes, when these voice parts move far apart, the voice stops making sound. We call these sounds "voiceless." But even when the voice doesn’t completely stop, the way the voice changes helps us understand these sounds. Special sounds like "glottal stops" happen when the voice parts come together, even if the voice doesn’t fully stop.

Physiology and vocal timbre

Everyone's voice sounds different because of the shape and size of their vocal cords and body, especially the part that shapes the sound. Skilled performers can even mimic these differences. Our voices change with how tight or loose our vocal cords are, and how we use our breath. The shape of our chest, neck, tongue, and even muscles we don’t think about can change how we sound.

Singers can learn to make their voices sound better by using special techniques called vocal resonance. The larynx, or voice box, also helps us make different sounds. This is why singers can use different vocal registers, which are ways of producing sound with the same vibration pattern of the vocal cords. These registers help create different pitches and tones.

Influences of the human voice

Main articles: Voice projection and Evolution

The twelve-tone musical scale, used in much of today’s music, might have started from the way people naturally sound when they speak. A study in 2021 looked at speech and found that the sounds people make match the notes in this musical scale. This shows how our voices may have helped shape music over time.

Voice disorders

Main articles: Vocal loading and Voice disorders

Many problems can affect the way we use our voices. Some people might have trouble speaking clearly, known as speech impediments, or they might develop small growths or injuries on the parts of the body that help us speak, called vocal folds. Talking too much or shouting for long periods can stress these important parts of our bodies.

When someone has trouble with their voice, a special doctor called an ENT might help, but the best way to keep your voice healthy is to use it carefully. A person trained to help with speech, called a speech-language pathologist, can also guide you on how to improve your voice.

Vocal cord nodules and polyps

Vocal nodules happen when we use our voices too roughly over time. This can create soft, swollen spots on the vocal cords that turn into harder growths called nodules. If this keeps happening, the nodules can grow bigger and stiffer. Polyps are usually larger and come from a single rough use of the voice. Sometimes they need surgery to remove them.

If you feel hoarse or your voice sounds breathy for more than two weeks, it’s best to see a doctor. Speech therapists can help teach ways to use your voice better and avoid these problems.