What Are Vowel Sounds?

High and Low Vowels

Linguists classify vowels by the position of the speaker's tongue in relation to the roof of the mouth. A high vowel leaves very little space between the tongue and the roof of the mouth. A low vowel seats the tongue low in the mouth, and a middle vowel is in between. The "ee" sound in "feet" is an example of a high vowel in English; the "a" in "ball" is an example of a low vowel. This is not to be confused with a vowel's high or low tone; in tonal languages, the pitch of a vowel actually changes the meaning of the word.

In linguistics, vowels are also classified by their backness, or the position of the tongue toward the front or back of the mouth. For example, English-speakers articulate certain vowels, such as the long O, with the tongue toward the back of the mouth. Other vowels, such as the "ee" sound, are made with the tongue toward the front. In English, the height and frontness of a vowel generally correlates with increased tension in the speaker's tongue.

The sound of a vowel depends on to what extent the speaker rounds his lips. Certain vowels in English, such as the long U and O, have a great degree of lip rounding. In English, vowels spoken with the tongue toward the back of the mouth tend to be more rounded than those spoken with the tongue toward the front. However, many languages make use of more vowel sounds than English does, and in some cases they use rounding to distinguish between two vowels of the same height or backness.

When a native English speaker is said to "talk through the nose," it's usually meant as an insult or seen as the unavoidable result of having a head cold. It makes the speaker's voice sound strange, but it doesn't change the meaning of his words. In other languages, however, nasalizing a vowel sound can create an entirely different word. Languages as diverse as French and Navajo make use of nasalized vowels. In French, for example, the difference between the words for "flax" and "milk" is the nasalization of the vowel sound.