(This is a provisional posting)
These two are mutually exclusive - if you get Yod Dropping you don't get Yod Coalescence, and vice-versa.
Yod Dropping REMOVES the j after t and d
Yod Coalescence happens when the j has NOT
dropped, but AFFRICATES the preceding t or d -
- so dew and Jew become homophones (=pronounced the same), and Tuesday is pronounced Choose-day.
Yod Dropping is common in North America, Yod Co in Britain.
Note that in older Cockney (up to the last third of the 20th century) Yod Dropping was common in Cockney; since then it has disappeared and Yod Coalescence has replaced it.
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