Cot–caught merger

IPA: Vowels
Front Central Back Close i y ɨ ʉ ɯ u Near-close ɪ ʏ ʊ Close-mid e ø ɘ ɵ ɤ o Mid ø̞ ə o̞ Open-mid ɛ œ ɜ ɞ ʌ ɔ Near-open æ ɐ Open a ɶ ä ɑ ɒ
IPA help  audio full chart template Vowels beside dots are: unrounded • rounded

The shift causes the vowel sound in words like cot, nod and stock and the vowel sound in words like caught, gnawed and stalk to merge into a single phoneme; therefore the pairs cot and caught, stock and stalk, nod and gnawed become perfect homophones, and shock and talk, for example, become perfect rhymes. The cot–caught merger is completed in the following dialects:

• Some dialects within the British Isles:
  • All Scottish English accents, towards [ɔ] (listen) (without the father–bother merger)[1]
  • Irish English broad and traditional accents, including:
    • Some northern Ulster English[1] including in conservative mid Ulster English towards [ä] (listen) and in Ulster Scots English towards [ɔ] (listen) (without the father–bother merger)[2]
• Many North American English accents:
  • Several accents of U.S. English, including:[3]
    • Pittsburgh English, towards [ɒ~ɔ] (with the father–bother merger)[4]
    • All New England English towards [ɑ~ɒ] (in Boston and Eastern New England, particularly towards [ɒ] (listen)), except in Rhode Island and southern Connecticut[3]
    • All Western American English (with the father–bother merger)[3]
    • Cajun English towards [ä] (listen).[5]
  • Nearly all Canadian English, including:[6]
    • Standard Canadian English towards [ɒ] (listen) (with the father–bother merger)
    • Maritimer and Newfoundland English, towards [ɑ~ä] (with the father–bother merger)
• Some Singaporean English (without the father–bother merger)[7]

On this map of English-speaking North America, the green dots represent speakers who have completely merged the vowels of cot and caught. The dark blue dots represent speakers who have completely resisted the merger. The medium blue dots represent speakers with a partial merger (either production or perception but not both), and the yellow dots represent speakers with the merger in transition. Based on the work of Labov, Ash and Boberg.[8]

Nowhere is the shift more complex than in North American English. The presence of the merger and its absence are both found in many different regions of the North American continent, where it has been studied in greatest depth, and in both urban and rural environments. The symbols traditionally used to transcribe the vowels in the words cot and caught as spoken in American English are ⟨ɑ⟩ and ⟨ɔ⟩, respectively, although their precise phonetic values may vary, as does the phonetic value of the merged vowel in the regions where the merger occurs.

Even without taking into account the mobility of the American population, the distribution of the merger is still complex; there are pockets of speakers with the merger in areas that lack it, and vice versa. There are areas where the merger has only partially occurred, or is in a state of transition. For example, based on research directed by William Labov (using telephone surveys) in the 1990s, younger speakers in Kansas, Nebraska, and the Dakotas exhibited the merger while speakers older than 40 typically did not.[9][10] The 2003 Harvard Dialect Survey, in which subjects did not necessarily grow up in the place they identified as the source of their dialect features, indicates that there are speakers of both merging and contrast-preserving accents throughout the country, though the basic isoglosses are almost identical to those revealed by Labov's 1996 telephone survey. Both surveys indicate that, as of the 1990s, approximately 60% of American English speakers preserved the contrast, while approximately 40% merged the phonemes. Further complicating matters are speakers who merge the phonemes in some contexts but not others, or merge them when the words are spoken unstressed or casually but not when they're stressed.

Speakers with the merger in northeastern New England still maintain a phonemic distinction between a fronted and unrounded /ɑ/ (phonetically [ä]) and a back and usually rounded /ɔ/ (phonetically [ɒ]), because in northeastern New England (unlike in Canada and the Western United States), the cot–caught merger occurred without the father–bother merger. Thus, although northeastern New Englanders pronounce both cot and caught as [kɒt], they pronounce cart as [kät].

Labov et al. also reveal that, for about 15% of respondents, a specific /ɑ/–/ɔ/ merger before /n/ but not before /t/ (or other consonants) is in effect, so that Don and dawn are homophonous, but cot and caught are not. In this case, a distinct vowel shift (which overlaps with the cot–caught merger for all speakers who have indeed completed the cot–caught merger) is taking place, identified as the Don–dawn merger.[11]

In London's Cockney accent, a cot–caught merger is possible only in rapid speech. The THOUGHT vowel has two phonemically distinct variants: closer /oː/ (phonetically [oː ~ oʊ ~ ɔo]) and more open /ɔə/ (phonetically [ɔə ~ ɔwə ~ ɔː]). The more open variant is sometimes neutralized in rapid speech with the LOT vowel /ɒ/ (phonetically [ɒ ~ ɔ]) in utterances such as [sˈfɔðɛn] (phonemically /ɑɪ wəz ˈfɔə ðen/) for I was four then. Otherwise /ɔə/ is still readily distinguished from /ɒ/ by length.[19]

Outside North America, another dialect featuring the merger is Scottish English. Like in New England English, the cot–caught merger occurred without the father–bother merger. Therefore, speakers still retain the distinction between /a/ and /ɔ/.

• Phonological history of English low back vowels

• Barber, Charles Laurence (1997). Early modern English (second ed.). Edinburgh: Edinburgh University Press. ISBN 0-7486-0835-4.
• Gordon, Matthew J. (2005), "The Midwest Accent", American Varieties, PBS, retrieved August 29, 2010
• Labov, William; Ash, Sharon; Boberg, Charles (2006). The Atlas of North American English: Phonetics, Phonology, and Sound Change: a Multimedia Reference Tool. Berlin ; New York: Walter de Gruyter. ISBN 3-11-016746-8.CS1 maint: ref=harv (link)
• Wells, John C. (1982), Accents of English, Volume 2: The British Isles (pp. i–xx, 279–466), Cambridge University Press, ISBN 0-52128540-2

• Map of the cot–caught merger from the 2003 Harvard Dialect Survey
• Map of the cot–caught merger from Labov's 1996 telephone survey
• Description of the cot–caught merger in the Phonological Atlas
• Map of the cot–caught merger before /n/ and /t/
• Chapter 13 of the Atlas of North American English, which discusses the "short-o" configuration of various American accents