Understanding Vowels: how they contribute to your child’s speech

Written by Jill Hicks, Speech-Language Pathologist, October 2024

Vowels Affect Intelligibility
As a class of sounds, vowels tend to be the easiest speech sounds to produce.  Hence they are usually among the first sounds babies make.  Being able to say a variety of vowels makes a child’s speech easier to understand.  Using the correct vowel(s) in a word increases speech intelligibility.  Having a basic understanding of how vowels are made can help parents and caregivers.  So let’s explore vowels.
The Articulators
A vowel is made based on the position of the articulators.  The articulators include the tongue, jaw, lips, palate, teeth and cheeks.  Vowels are made when two articulators approach each other. Air exhaled from the lungs moves through the opening left by the articulators. 
Continuants
Vowels are continuant sounds. This means they do not have a precise stopping point in time.  Vowels can continue on until the exhaled air runs out.
Voiced
All vowels are made with the vocal folds vibrating.  The vocal folds vibrate rapidly in the larynx, or voicebox, creating a source of sound.  All vowels are voiced sounds.
Jaw Position
How open or closed the jaw is affects which vowel is produced.  Vowels produced with the most open jaw posture are “a” (as in apple) and “o” (as in on). 
Tongue Position
The tongue position affects which vowel is produced.  The tongue can be classified according to its vertical position – high, mid or low in the mouth.  The tongue can also be classified according to its horizontal position – front or back of the mouth.
Lips
What the lips do affects what sound is made.  The lips can be retracted (smiling) as in “ee”. The lips can be rounded as in “oe”.  The lips can be wide open as in “o”.

Speech-language pathologists refer to a handy visual that shows the position of the tongue during vowel production.  The space in the oral cavity is represented by a trapezoid shape.  Imagine the left side (red line) being the front of the mouth.  The right side (black line) represents the back of the mouth.  The blue line represents the top of the mouth or palate.  The green line represents the floor of the mouth.

​When the tongue is high in the front of the mouth “ee” is produced.  When the tongue is high in the back of the mouth “ew” is produced.  “a” (as in ant) is the low front vowel.  “o” (as in on) is the low back vowel.

The Most Neutral Vowel
If you open your mouth slightly and make a voiced sound it will be the “u” sound (as in up).  This is also called the schwa sound.  “u” is the most neutral vowel, made when the mouth is in the most neutral position.

When We Use Schwa
Schwa is the vowel in many words such as up, cup, hut, puff, sun, one, etc.  But here’s an interesting thing – we also use schwa in many multisyllabic words.  Using the easiest to produce, most neutral vowel makes longer words easier to say.  Here are some examples.  We don’t say ba-na-na.  We actually say bu-na-nu.  The first and last vowels are “reduced” to schwas in spoken language.  Another example is elephant.  We don’t say el-e-phant.  We say el-u-phunt, reducing the last two (unstressed) vowels to schwas.
Attuning Our Ears
When listening to a child’s speech, as parents we tend to listen for meaning.  We try to figure out what word our child is trying to say.  We aren’t specifically listening for exactly how the sounds are made.
When a child is working to produce a specific sound in words, it helps if the adult listener attunes his or her ears to analyze how the child is saying the sound.  For example, for the word dog, we may interpret our child’s speech as having said dog.  But when we analyze the actual speech production we realize they said something a bit different such as do, du, dug, or maybe gog. 
If we’re practicing clear production of the “o” (as in on) vowel, then the child’s production of u (the neutral vowel) needs to be refined and replaced with the “o” vowel sound. 
It takes intentional practice to attune our ears to how our child actually says the word.  In the case of a substitution of dug for dog, we would need to help the child lower the jaw to make the low “o” vowel instead of the mid “u” vowel sound.
Vowels Have a Big Impact
When we think of refining our child’s speech we often think of the consonants.  However it is also important to take the time to work on vowel production.  Vowels have a big impact on speech intelligibility.  Your child’s speech-language pathologist will determine which phonemes to work on and if needed will likely include vowels.