Is the pronunciation difference between “BrE deuce” vs “AmE deuce” systematic?

Solution 1:

The elision of /j/ in deuce etc. in North American English is known as yod-dropping and occurs after coronal consonants (those that involve the tongue tip, i.e. /t, d, n, s, z, θ, l/) within the same syllable.

This makes dew/due and tune homophonous with do and toon, respectively. It is present in all of North America except some parts of the Southern US.

/r/ is also a consonant that involves the tongue tip, and rude, brew, true, etc. used to be pronounced with /j/, but it's now completely gone even in British English. /j/ after /s/ and /l/, as in suit and lute, is also disappearing in BrE too.

A related phenomenon observed in Englishes outside North America is yod-coalescence, by which /tj, dj, sj, zj/ become /tʃ, dʒ, ʃ, ʒ/. This makes dew/due homophonous with Jew instead and Tuesday sound like choose day. Yod-coalescence in words traditionally pronounced with /tj, dj/ such as tune and dune used to be considered substandard or rural in British English, but has since gained wide currency and is now considered part of the standard(ized) variety of Southern British English (though pronunciation with /j/ is still common). Words like nature and vision also used to be pronounced with /j/ but yod-coalescence in these words is complete in almost all accents worldwide.

Solution 2:

Consider tune in AmE and BrE: in the latter it is like tyune /tjuːn/ (in AmE it is /tuːn/). This pronunciation after a dental /t/, /d/ and before U is a known difference, although I dont know the exact contexts in which it happens.

See also Quora's Why do British speakers insert a "y" before the letter "u" when pronouncing...

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