Vowel Modification for Singers

How to Sing More Powerfully and Transition More Smoothly Throughout Your Range

Gospel Singer
© 2014 by Lisa Haupert. All Rights Reserved.

Our voices are mysterious instruments because we can’t see how they work. Consequently, few singers actually know how to get the most out of their voices to reach their artistic goals. One area that is crucial to mastering your singing is vowel modification. You can learn how to subtly “tune” your vowels so that you can sing with more power and navigate the transition areas or “registers” of your voice smoothly.

Mastering subtle vowel modification is a critical part of your artistic development so that you can use your singing voice in the exact way you desire. 

Sound waves are produced by the vibration of the air molecules that pass between the vocal folds (cords) when we sing or speak. But it is the vocal tract (the throat and mouth) that magnifies the sound that is produced by the vocal folds.

The sound that is produced at the vocal folds without the filtering of the vocal tract sounds similar to a duck call. The vocal tract is divided into two sections: the throat and the mouth. It takes the resonances of both of those areas to make a vowel. Here is a delightful demonstration using duck calls that are shaped similarly to the vocal tract to make different vowel sounds.

There are multiple frequencies within each sound wave that our vocal folds produce. The fundamental pitch is the “note” that we hear.

But there are many other pitches within that sound wave. For example, if a note produced by the human voice has a pitch of 200 Hz, it will have not only the fundamental pitch of 200 Hz, but also many other frequencies that are integer multiples of that value (e.g. 200, 400, 600, 800, 1000 Hz). 

The human brain translates all of those pitches back to the fundamental frequency, which in this case is 200 Hz (around a G below middle C).

It interprets the rest of the frequencies (the harmonics higher than the fundamental frequency) as the “color” or “character” of the sound.

When we sing, the entire spectrum of frequencies of the complex sound wave that our vocal folds create travel through the variously sized areas in the vocal tract. Some of these frequencies will resonate more than others as they interact with the resonant areas in the tract. Larger spaces resonate at lower frequencies; smaller spaces resonate at higher frequencies.

The two largest spaces of the vocal tract are the throat and the mouth. They produce the two lowest resonant frequencies, also called “formants.” The first formant, F1,  is the resonant frequency of the throat and the second formant, F2,  is the resonant frequency of the mouth.

When we shape our vowels so that they tune to the resonance of the vocal tract, there is a boost in certain harmonics of the fundamental pitch. Any harmonic at a frequency near that of a formant gets boosted.

There are specific ways that formant frequencies can be changed. These are done through vowel modification. (See the attached "Vowel Chart.")

  1. We can decrease or lower both F1 and F2 by increasing the length of the vocal tract. This happens when we lower the larynx and when we push the lips forward. An example of this is the vowel “oo,” produced with slightly protruded lips and a round mouth shape.
  1. We can increase or raise both F1 and F2 by decreasing the length of the vocal tract. This happens when we raise the larynx and when we spread the lips wide. An example of this is the vowel sound in the American pronunciation of “mad.”
  2. We can raise F1 by dropping our jaw.  Sing the vowel “ah” as in “ball” and then drop your jaw. You will hear quite a dramatic change in the sound.
  3. Making the mouth resonator smaller lowers F1 and raises F2. This happens with the vowels [i] as in “eat” and [e] as in “ate.”
  4. Making the throat resonator smaller raises F1 and lowers F2. This happens with the vowels “ah” as in “father” and “oh” as in “go.”

For more detail go to: http://ncvs.org/e-learning/tutorials/modifying.html.

Transition Smoothly between Vocal Registers

One of the primary applications of vowel modification is to help the singer transition smoothly between vocal registers.

By subtly using vowel modification you can move through the “passagi” or “bridges” of the voice without a break or flip. The physical sensation of the primary resonance moving from the throat to the mouth is what we experience as the transition between our chest and head voices.

When singers do not modify the vowels as they approach the transition area of their voice they either simply cannot sing any higher or they have a dramatic change in the quality of their voice. By adjusting the shape of the two resonators (the mouth and throat) a singer can learn how to smoothly transition between registers. This takes some experimentation.

Sing More Powerfully throughout Your Range

Subtle vowel modification is also an essential component of producing a powerful or ringing voice. When we adjust our vowel so that the higher harmonics are boosted, the human ear registers the sound as being more powerful than the exact same fundamental pitch that has lower harmonics boosted.

This, too, requires the singer to experiment. The shades of vowel tuning are all but infinite and the adjustment of resonators to get the greatest harmonic boost is specific to each individual. It takes exploration, but once you discover the sweet spot for each pitch with each vowel, you will eventually develop a sensory memory for that and will be able to repeat it.

In summary, the power of your singing and the ease with which you navigate the transition areas of your voice are directly tied to the resonance in your throat and mouth. That resonance, in turn, is influenced by how you form your vowels. By modifying your vowels appropriately, you can increase the strength and power of your singing; you can also eliminate “breaks” or “flips” in your voice as you transition from your chest to your head voice.


Lisa Haupert is the founder of Shameless Singing and the education manager for Vocology in Practice. Her passions are teacher education and artist vocal development. She maintains studios in Nashville, TN, Asheville, NC and everywhere else via Skype.