You already know by now, that all vowel sounds are produced without any obstruction of the airstream and that all vowel sounds are voiced. The only articulator of our vocal tract involved in the production of vowels, are the tongue and to some extent the lips.
Source of the picture: wikipedia.org
However, in phonetic terms, each vowel has a number of properties that distinguish it from other vowels. Especially the position of the tongue (raised or lowered), but also the shape of the lips (rounded or unrounded) determine the quality of a vowel (there is, after all, a reason why a photographer makes you say cheese) In the following subchapters we will have a closer look at how we can describe and categorize English vowel sounds in terms of their articulation and lip posture. We will also learn about more complex vowel articulation, namely diphthongs and triphthongs.
Vowel Articulation The position of the tongue is one of the most important features that we can use in order to describe and understand how the different vowels of the English sound system are produced. Have a look at this subchapter for a little tongue-training.
Vowel Lip Posture Have you ever really paid attention to the movements of your lips when you say a e i o u? Did you ever ask yourself, how ventriloquists manage to speak without moving their lips? How important is lip posture for the production of speech sounds? Have a look at this subchapter, and you will find out!
Complex Vowel Articulations In addition to the so called pure or plain vowels, most English accents have 8 vowel sequences consisting of two sounds. Diphthongs are characterized by a change of quality, starting with one sound and moving to another. You will learn more about how diphthongs (and triphthongs) are produced and how they can be described in this subchapter.