Cot–caught merger in the context of "New England English"

The open-mid back rounded vowel, or low-mid back rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɔ⟩. The IPA symbol is a turned letter c and both the symbol and the sound are commonly called "open-o". The name open-o represents the sound, in that it is like the sound represented by ⟨o⟩, the close-mid back rounded vowel, except it is more open. It also represents the symbol, which can be remembered as an o which has been "opened" by removing part of the closed circular shape.

In English, the symbol ⟨ɔ⟩ (or ⟨ɔː⟩) is typically associated with the vowel in "thought", but in Received Pronunciation ("RP", standard British English), Australian English, New Zealand English and South African English that vowel is produced with considerably stronger lip rounding and higher tongue position than that of cardinal [ɔ], i.e. as close-mid [oː] or somewhat lower. Open-mid [ɔː] or even open [ɒː] realizations are found in North American English (where this vowel is often indistinguishable from the open back unrounded vowel in "bra") and Scottish English as well as Hiberno-English, Northern England English and Welsh English, though in the last three accent groups closer, [oː]-like realizations are also found. In RP, the open-mid realization of /ɔː/ has been obsolete since the 1930s. Pronouncing that vowel as such is subject to correction for non-native speakers aiming at RP.

Midland American English is a regional dialect or supradialect of American English, geographically lying between the traditionally defined Northern and Southern United States. The boundaries of Midland American English are not entirely clear, being revised and reduced by linguists due to definitional changes and several Midland sub-regions undergoing rapid and diverging pronunciation shifts since the early-middle 20th century onwards.

As of the early 21st century, these general characteristics of the Midland regional accent are firmly established: fronting of the /oʊ/, /aʊ/, and /ʌ/ vowels occurs towards the center or even the front of the mouth; the cot–caught merger is neither fully completed nor fully absent; and short-a tensing evidently occurs strongest before nasal consonants. The currently documented core of the Midland dialect region spans from central Ohio at its eastern extreme to central Nebraska and Oklahoma City at its western extreme. Certain areas outside the core also clearly demonstrate a Midland accent, including Charleston, South Carolina; the Texan cities of Abilene, Austin, and Corpus Christi; and central and some areas of southern Florida.

Western New England English refers to the varieties of New England English native to Vermont, Connecticut, and the western half of Massachusetts; New York State's Hudson Valley (from Albany to Poughkeepsie) also aligns to this classification. Sound patterns historically associated with Western New England English include the features of rhoticity (full pronunciation of all r sounds), the horse–hoarse merger, and the father–bother merger, none of which are features traditionally shared in neighboring Eastern New England English. The status of the cot–caught merger in Western New England is inconsistent, being complete in the north of this dialect region (Vermont), but incomplete or absent in the south (southern Connecticut), with a "cot–caught approximation" in the middle area (primarily, western Massachusetts).

Western New England English is relatively difficult for most American laypersons and even dialectologists to identify by any "distinct" accent when compared to its popularly recognized neighbors (Eastern New England English, New York City English, and Inland Northern U.S. English), meaning that its accents are typically perceived as unmarked "General American" varieties. Linguistic research, however, reveals that Western New England English is not simply one single or uniform dialect. Linguist Charles Boberg proposes that it be most generally divided into a Northwestern New England English (a standalone "Vermont" accent) and a Southwestern New England English (a less advanced subdialect of Inland Northern English); however, even Boberg lists the possibilities of several distinct accent divisions of Western New England.

Standard Canadian English is the largely homogeneous variety of Canadian English that is spoken particularly across Ontario and Western Canada, as well as throughout Canada among urban middle-class speakers from English-speaking families, excluding the regional dialects of Atlantic Canadian English. Canadian English has a mostly uniform phonology and much less dialectal diversity than neighbouring American English. In particular, Standard Canadian English is defined by the cot–caught merger to [ɒ] and an accompanying chain shift of vowel sounds, which is called the Canadian Shift. A subset of the dialect geographically at its central core, excluding British Columbia to the west and everything east of Montreal, has been called Inland Canadian English. It is further defined by both of the phenomena that are known as Canadian raising (which is found also in British Columbia and Ontario): the production of /oʊ/ and /aʊ/ with back starting points in the mouth and the production of /eɪ/ with a front starting point and very little glide that is almost [e] in the Canadian Prairies.