It is the vowels that differ most from region to region.
- American English lacks this sound; words with this sound are pronounced with /ɑ/ or /ɔ/.
- Many dialects of North American English do not have this vowel. See Cot-caught merger.
- The North American variation of this sound is a rhotic vowel.
- Many speakers of North American English do not distinguish between these two unstressed vowels. For them, roses and Rosa's are pronounced the same, and the symbol usually used is schwa /ə/.
- This sound is often transcribed with /i/ or with /ɪ/.
- The diphthongs /eɪ/ and /oʊ/ are monophthongal for many General American speakers, as /eː/ and /oː/.
- The letter <U> can represent either /u/ or the iotated vowel /ju/. In BRP, if this iotated vowel /ju/ occurs after /t/, /d/, /s/ or /z/, it often triggers palatalization of the preceding consonant, turning it to /ʨ/, /ʥ/, /ɕ/ and /ʑ/ respectively, as in tune, during, sugar, and azure. In American English, palatalization does not generally happen unless the /ju/ is followed by r, with the result that /(t, d,s, z)jur/ turn to /tʃɚ/, /dʒɚ/, /ʃɚ/ and /ʒɚ/ respectively, as in nature, verdure, sure, and treasure.
- Vowel length plays a phonetic role in the majority of English dialects, and is said to be phonemic in a few dialects, such as Australian English and New Zealand English. In certain dialects of the modern English language, for instance General American, there is allophonic vowel length: vowel phonemes are realized as long vowel allophones before voiced consonant phonemes in the coda of a syllable. Before the Great Vowel Shift, vowel length was phonemically contrastive.
- This sound only occurs in non-rhotic accents. In some accents, this sound may be, instead of /ʊə/, /ɔ:/. See pour-poor merger.
- This sound only occurs in non-rhotic accents. In some accents, the schwa offglide of /ɛə/ may be dropped, monophthising and lengthening the sound to /ɛ:/.
- International Phonetic Alphabet for English for more vowel charts.