The Great Vowel Shift was a major change in the pronunciation of the English language that took place in England between 1350 and 1700. The Great Vowel Shift was first studied by Otto Jespersen (1860–1943), a Danish linguist and Anglicist, who coined the term.
Because English spelling was becoming standardized in the 15th and 16th centuries, the Great Vowel Shift is responsible for many of the peculiarities of English spelling.
The main difference between the pronunciation of Middle English and Modern English is in the value of the long vowels, described as the Great Vowel Shift. Vowels of Middle English had “continental” values much like those remaining in Spanish and liturgical Latin. However, during the Great Vowel Shift, the two highest long vowels became diphthongs, and the other five underwent an increase in tongue height…
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