Phonological history of English vowels

In the history of English phonology, there were many diachronic sound changes affecting vowels, especially involving phonemic splits and mergers.

The Great Vowel Shift was a series of chain shifts that affected historical long vowels but left short vowels largely alone. It is one of the primary causes of the idiosyncrasies in English spelling.

The shortening of ante-penultimate syllables in Middle English created many long–short pairs. The result can be seen in such words as,

*Earlier Modern English /ou/ merged with /oː/.

Tense–lax neutralization refers to a neutralization, in a particular phonological context in a particular language, of the normal distinction between tense and lax vowels.

In some varieties of English, this occurs in particular before /ŋ/ and (in rhotic dialects) before coda /r/ (that is, /r/ followed by a consonant or at the end of a word); it also occurs, to a lesser extent, before tautosyllabic /ʃ/.

In the Pacific Northwest, especially in the Seattle area, some speakers have a merger of /ɛ/ with /eɪ/ before /ɡ/. For these speakers, words with /ɛ/ like beg, egg, Greg, keg, leg and peg rhyme with words with /eɪ/ like Craig, Hague, plague and vague.

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