Canadian raising

Canadian raising (also sometimes known as English diphthong 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 aɪ or aʊ, or both, when they are pronounced before voiceless consonants (therefore, in words like price and clout, respectively, but not in prize and cloud). In North American English, /aɪ/ and /aʊ/ usually begin in an open vowel [ä~a], but through raising they shift to ɐ, ʌ or ə. Canadian English often has raising in words with both aɪ (height, life, psych, type, etc.) and aʊ (clout, house, south, scout, etc.), while a number of American English varieties (such as Inland North, Western New England, and increasingly more General American accents) have this feature in aɪ but not aʊ. It is thought to have originated in Canada in the late 19th century. In the U.S., aboot [əˈbut], an exaggerated version of the raised pronunciation of about [əˈbʌʊt], is a stereotype of Canadian English. Although the symbol is defined as an open-mid back unrounded vowel in the International Phonetic Alphabet, or may signify any raised vowel that contrasts with unraised aɪ or aʊ, when the exact quality of the raised vowel is not important in the given context. In general, Canadian raising affects vowels before voiceless consonants like f, θ, t, and s. Vowels before voiced consonants like v, ð, d, and z are usually not raised. However, several studies indicate that this rule is not completely accurate, and have attempted to formulate different rules. A study of three speakers in Meaford, Ontario, showed that pronunciation of the diphthong aɪ fell on a continuum between raised and unraised. Raising is influenced by voicing of the following consonant, but it may also be influenced by the sound before the diphthong. Frequently the diphthong was raised when preceded by a coronal: in gigantic, dinosaur, and Siberia. Raising before /r/, as in wire, iris, and fire, has been documented in some American accents.