Regional dialects are a matter of common knowledge for most Americans, and while people often share the name for a dialect, there is less agreement about where the dialect is spoken, who speaks it, or what features it has. Traditional American dialects follow long established patterns, but they owe more to perceptions than to what people actually say in different places. The complex system of American English gives rise to the possibility to notice what people perceive to be dialects.

This chapter introduces diphthongs as well as other English vowels that only occur in specific positions. Unlike for monophthongs, where the tongue remains in a steady position, for diphthongs the tongue performs a gliding movement during articulation. Diphthongs are an integral part of the English vowel system. Sometimes diphthongs are indicated in the spelling by a digraph, such as in they. At other times, however, they are represented by a single vowel letter, as in gave. Two classes of vowels deserve special attention, as they only occur in specific positions. Pre-rhotic vowels only occur when in spelling the vowel is followed by ‹r›. Weak vowels, on the other hand, only appear in unstressed syllables, so in syllables that are not accentuated. Finally, the chapter looks at letter-to-sound correspondences. These are more intricate, as the thirteen vowel qualities found in English can only be written with the five vowel letters of the Latin alphabet. However, they are also more regular than might be assumed.