What are formants and why are they important?

In my blog “What Happens When We Make A Sound?” I discussed how the vocal folds create a frequency that determines our pitch and in my blog “What are Harmonics?” we discovered that the vocal folds actually vibrate at multiple frequencies at once that determine the tone of the sound. But this isn’t the end of the puzzle, welcome to the world of Formants.

0713f5813981a7f2ad103f174c495bba--ks-science-kindergarten-science.jpg

If you blow across the top of bottles filled with different amounts of liquid, different pitches are formed. When we blow into the bottle, it causes the air to vibrate and therefore a sound wave to be created. It forms what we call a resonator. Depending on the size, shape, density of the walls and size of the opening of the bottle different frequencies are boosted and therefore different pitches are produced.

What is a Resonator?

Before we work out how this related to the voice, it is essential to understand what a resonator is. A resonator does not create the vibration and therefore does not generate the frequency. In the example of the bottles, it is the action of blowing into the bottle that causes the air to vibrate and produce sound. Most instruments have a container of air or resonator, think of the body of a guitar. As with the bottles, the smaller the space in the tank, the higher the pitch and the bigger the space, the lower the pitch. Think of the instruments of the orchestra, with big instruments like the double bass and the tuba making low sounds and the piccolo making a high sound.

Formants vs Harmonics?

Formants: As we have discovered, the air inside the vocal tract vibrates at different pitches depending on its size and shape of the opening. We call these pitches formants. You can change the formants in the sound by changing the size and shape of the resonator, or in our case the vocal tract.

Harmonics: Harmonics are produced by the vocal folds themselves. You can change the harmonics present in the sound by changing the shape of the vocal folds and therefore the pitch being created. More closure in the vocal folds will produce stronger, higher harmonics.

It is important to note that when a sound wave meets another sound wave that is similar to the one they want to vibrate at, they join in with that vibration. So when a similar formant meets a harmonic, they join in vibration. When two sound waves join together the sound wave is strengthened.

How does this relate to the voice?

This is all very well, but how is this going to help us make a more beautiful sound? Like other instruments, we have our very own resonator, the vocal tract. Like the glass bottle, certain frequencies can be boosted by the size, shape, density of the walls of the vocal tract and the size of the opening (our mouths). The formants produced in the vocal tract filter the original sound source from the vocal folds. After the harmonics go through the vocal tract, some harmonics join with formants become louder and others are not boosted become softer. This changes the tone of the sound.

Every human has a slightly different shape and size of vocal tract. This is what gives us our unique tone. The fun thing is unlike the bottle, our vocal tract is very malleable and we have the choice to change and adapt our tone as we like. Although we have to work with our own vocal tract and its own unique signature, this allows us to create vocal pictures with multiple tones and qualities.

Watch out for my next blog, in which I will help you discover what tones you can create and how to do it.