Vowel phonemes are a class of speech sounds that are voiced and open—meaning, vowel sounds are produced with no obstruction of the airflow through the mouth. There are 15 vowel phonemes in English, plus r-controlled vowel combinations (i.e., /er/, /ar/, and /or/) and the schwa (/ǝ/). The schwa is an indistinct, unaccented vowel sound, often described as a muffled /ŭ/ or /ĭ/ sound. In the English language system, every spoken and written syllable includes a vowel sound.
English vowels can be distinguished by tongue position (front, middle, or back), tongue height (high, low), and lip shape (rounded and unrounded). The vowels in the image below are arranged by point of articulation.
Source: Moats, L. (2020) From Speech to Print: Language Essentials for Teachers (p. 135). Baltimore, MD: Paul H. Brookes.
- Front: The first vowel represented on the chart, /ē/, is formed at the front of the mouth with the tongue high and the lips in an unrounded smile position. With pronunciation of the next five vowels in the sequence—/ǐ/, /ā/, /ĕ/, /ă/, and /ī/—the tongue drops and the mouth opens into a wider, more rounded position.
- Low, Middle: The vowel /ŏ/, as in fox, father, and palm, is pronounced with the tongue low and the lips open. The vowel /ǔ/, as in cup, cover, and flood, is similarly a low, middle vowel.
- Back, Rounded: The next five vowels in the sequence—/au/ or /aw/, /ō/, /oo/, /ū/, and /yū/ are rounded, back vowels pronounced from further back in the throat and the lips in a rounded shape.
- Diphthong: The diphthongs—/oi/ and /ou/—are single vowel phonemes that glide in the middle. Because the position of our mouth changes as we pronounce these vowels, they do not fit cleanly into the sequence outlined above. Try it! Say /ou/ as in wow slowly and notice how your mouth shifts from wide open to rounded. That’s the glide in action.
- r-Controlled: These vowel phonemes—/ir/, /er/, /ur/, /ar/, and /or/—are categorized independently because the the combination of a vowel sound followed by /r/ often changes the vowel sound and results in a single, indivisible phoneme.
