Aboot

Canadian raising is an allophonic rule of phonology in many varieties of North American English that changes the pronunciation of diphthongs with open-vowel starting points. Most commonly, the shift affects or, or both, when they are pronounced before voiceless consonants. In North American English, and usually begin in an open vowel [~], but through raising they shift to, or. Canadian English often has raising in words with both and, while a number of American English varieties have this feature in but not. It is thought to have originated in Canada in the late 19th century.

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