English pronunciation includes the usage of consonant and vowel sounds in the English language. Like all languages, spoken English has wide variation in its pronunciation both diachronically and synchronically from dialect to dialect. This variation is especially salient in English, because the language is spoken over such a wide territory, being the predominant language in the United Kingdom, Ireland, Canada, the United States, Australia, and New Zealand in addition to being spoken as a first or second language by people in countries on every continent. With no conclusive, internationally recognized standards for English, even the English spoken in different countries can occasionally prove to be an impediment to understanding what is said, although for the most part the different regional accents of English are mutually intelligible.

The number of speech sounds in English varies from dialect to dialect, and any actual tally depends greatly on the interpretation of the researcher doing the counting. The Longman Pronunciation Dictionary by John C. Wells, for example, using symbols of the International Phonetic Alphabet, denotes 24 consonants and 23 vowels used in Received Pronunciation, plus two additional consonants and four additional vowels used in foreign words only. For General American it provides for 25 consonants and 19 vowels, with one additional consonant and three additional vowels for foreign words. The American Heritage Dictionary, on the other hand, suggests 25 consonants and 18 vowels (including r-colored vowels) for American English, plus one consonant and five vowels for non-English terms [1].

Around the late 14th century, English began to undergo the Great Vowel Shift, in which the high long vowels and [uː] in words like price and mouth became diphthongized, first to [əɪ] and [əʊ] (where they remain today in some environments in some accents such as Canadian English) and later to their modern values [aɪ] and [aʊ]. The other long vowels became higher: [eː] became [iː] (e.g. meet), [aː] became [eː] (later diphthongized to [eɪ], e.g. name), [oː] became [uː] (e.g. goose), and [ɔː] become [oː] (later diphthongized to [oʊ], e.g. bone). Later developments complicate the picture: whereas in Geoffrey Chaucer's time food, good, and blood all had the vowel [oː] and in William Shakespeare's time they all had the vowel [uː], in modern pronunciation good has shortened its vowel to [ʊ] and blood has shortened and lowered its vowel to [ʌ] in most accents. In Shakespeare's day (late 16th-early 17th century), many rhymes were possible that no longer hold today. For example, in his play The Taming of the Shrew, shrew rhymed with row.

Stress changes in many English words came about when the word was used as either a noun or a verb. For example, a rebel (stress on the first syllable) is inclined to rebel (stress on the second syllable) against the powers that be. The number of words using this pattern as opposed to only stressing the second syllable in all circumstances doubled every century or so, now including the English words object, convict, and addict.

Although regional variation is very great across English dialects, some generalizations can be made about pronunciation in all (or at least the vast majority) of English accents:

• The voiceless stops /p t k/ are aspirated at the beginnings of words (e.g. tomato) and at the beginnings of word-internal stressed syllables (e.g. potato).
• A distinction is made between tense and lax vowels in pairs like beet/bit and bait/bet, although the exact phonetic implementation of the distinction varies from accent to accent.
• Wherever [r] originally followed a tense vowel or diphthong (in Early Modern English) a schwa offglide was inserted, resulting in centering diphthongs like [iə] in beer [biər], [uə] in poor [puər], [aɪə] in fire [faɪər], [aʊə] in sour [saʊər], etc. This phenomenon is known as breaking. The subsequent history depends on whether the accent in question is rhotic or not: In nonrhotic accents like RP the postvocalic [r] was dropped, leaving [biə, puə, faɪə, saʊə] and the like (now usually transcribed [bɪə, pʊə] etc.). In rhotic accents like General American, on the other hand, the [ər] sequence was coalesced into a single sound, a nonsyllabic [ɚ], giving [biɚ, puɚ, faɪɚ, saʊɚ] and the like (now usually transcribed [bɪɹ, pʊɹ, faɪɹ, saʊɹ] etc.). As a result, originally monosyllabic words like those just mentioned came to rhyme with originally disyllabic words like seer, doer, higher, power.
• In many (but not all) accents of English, a similar breaking happens to tense vowels before [ɫ], resulting in pronunciations like [piəɫ] for peel, [puəɫ] for pool, [peəɫ] for pail, and [poəɫ] for pole.

See also

• Happy tensing
• Caught-cot merger
• Rhotic and non-rhotic accents
• Received Pronunciation
• International Phonetic Alphabet for English
• IPA chart for English
• Phonemic differentiation in English