Canadian raising

Canadian raising is a vowel shift in many dialects 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, something like the vowel in alm [a], but through raising they shift to a sound similar to the vowel in um: [ɐ], [ʌ], or sometimes even [ɜ] or [ə]. Canadian English often has raising in both the PRICE word set (including words like height, life, psych, type, etc.) and MOUTH word set (clout, house, south, scout, etc.), but most dialects in the United States have raising only in the PRICE word set.