Speech-Language Pathology Topics: Vowels

What are vowels and why are they important to speech?

A vowel is a sound produced with a relatively open vocal tract. In contrast, consonant sounds are produced by constricting or interrupting the air flow at some point during production. You can maintain a vowel until you run out of breath. For example, take a deep breath and say "eeeeee" for as long as you can. You can keep making that sound until you get bored or until you run out of breath. However, when you make the "p" sound, you can't draw it out. You simply make the sound once and then have to move on. Vowels are essential to speech because they are the core of every syllable we make. Every word has at least one vowel. When vowels are produced incorrectly, that makes speech very difficult to understand.

What are the characteristics of vowels?

What makes an "e" different than an "o"? The vowel sounds are different from each other because you change the shape of your mouth when making each vowel. There are two main ways you change the shape of your mouth. Some vowels are made in the front of the mouth, some in the center, and some in the back. At the same time, some are made with the mouth relatively closed while some are made with the mouth relatively open. Speech-Language Pathologists use a vowel chart to keep track of the vowels and their characteristics.

If you say "beeeeeeee" and then say "baaaaaaaa" (as in "bat") you'll notice that you open your mouth more to make the "baaaaaa" sound. Next, say "beeeeeee" again and then "baaaaaaa" (as in "body"). This time you'll notice that the first sound is made in the front of the mouth while the second is made in the back.

What is the difference between a simple vowel and a diphthong?

A simple vowel is a sound made by keeping your mouth in a single position. When making a diphthong vowel, your mouth changes position. So, when making the /aI/ sound as in "bike" your mouth starts in a very open position and then closes for the second half of the diphthong. This second chart shows the five common diphthongs in American English and how they move in the mouth.

Why are vowel characteristics important to understand when planning therapy for Childhood Apraxia of Speech?

First of all, understanding the characteristics of vowels can help you understand why some vowels are harder than others for your child. Diphthongs are going to be harder than simple vowels because they require more complicated motor planning. If your child has an easier time with front sounds, they'll probably have an easier time with front vowels. If you are trying to help your child learn a back consonant (like /k/) it should be easier for them to make when paired with a back vowel because that makes the motor planning simpler.

Remember that Childhood Apraxia of Speech is fundamentally a problem with the motor planning of speech. The child has to form a motor plan to get from one sound to the next in a word including the consonants and the vowels. So if your child is working on /b/ words, the motor planning will be different if they are saying "bee" instead of "boo" because the vowels are produced in completely different ways. When you set up practice word lists, you want to pair /b/ with as many different vowels as possible to maximize generalization.

You might also be interested in the following articles:

Voicing Pairs

Random Example of the Complexity of Motor Planning