Father-Bother and Cot-Caught Mergers

Two common mergers in English are the father-bother and cot-caught mergers. The first is almost universal in North America. The second is almost universal in Canada and common in the western and southern United States. In the United Kingdom, many speakers lack the merger. Let us explore the differences between the two mergers.

Received Pronunciation does not have the father-bother merger or the cot-caught merger. Here are the phonetic transcriptions of these four words in Received Pronunciation:

father [fɑðə] bother [bɔ:ðə] cot [kɒt] caught [cɔ:t]

In Received Pronunciation father has an unrounded vowel and bother has a rounded one. However, in the case of cot and caught, both words have a rounded vowel.

In North America, many speakers have the two mergers. However, speakers in New York and Boston do not. However, these speakers  lack the low back rounded vowel of Received Pronunciation. They use the low back unrounded vowel in father instead.

Almost all speakers in Canada as well as those from the western and southern United States have the father-bother and cot-caught mergers. Here are the phonetic transcriptions of the four words for those with the mergers:

father [fɑðɚ] bother [bɑðɚ] cot [kɑt] caught [kɑt]

Speakers who have the father-bother and cot-caught mergers use the same vowel in all four words. On the other hand, those who lack the merger such as speakers of Received Pronunciation, use different vowels. In Received Pronunciation, bother and caught have the same vowel, but father and cot do not. In cot, Received Pronunciation uses a vowel which North American English does not have.