Yod coalescence

Yod is the name of the smallest letter in the Hebrew alphabet – it stands for the vowel /iː/ or the semi-vowel /j/. In English phonetics Yod coalescence is a form of assimilation, a phenomenon which takes place when /j/ is preceded by certain consonants most commonly /t/ and /d/:

/t/+/j/ -> /ʧ/
 What you need. /wɒˈʧu niːd/
 The ball that you brought. /ðə ˈbɔːl ðəˈʧuː brɔːt/
 But use your head! /bəˈʧuːz jə hed/
 Last year /lɑːsˈʧɪə/

/d/+/j/ -> /ʤ/
 Could you help me? /kʊʤu ˈhelp miː/
 Would your brother come? /wʊʤɔː ˈbrʌðə kʌm/
 Had you been there before? /hæʤuː ˈbiːn ðeə bɪˈfɔː/
 In second year /ɪn ˈsekənʤɜː/

In a similar way /s/ + /j/, and /z/ + /j/ can sometimes be pronounced as /ʃ/ and /ʒ/ respectively, but this is less common and not of great interest to the foreign student of English.

Yod coalescence is common in colloquial speech and is becoming ever more so. Note that it can occur within words (e.g. tube /tjuːb/ = /tʃuːb/) and between word boundaries (as in the above examples). The fact that two extremely recurrent words in English, you and your, start with /j/ means that understanding of this simple mechanism is vital to the understanding of spoken English. Do you is often pronounced as /dʒə/:

 Do you live here? /ʤə ˈlɪv hɪə/

Identify places where yod coalescence may occur in the following phrases and then listen:
 What you need is a good job!
 You told me that you had your homework done.
 She didn't go to France that year.
 Could you open the window please?
 You've already had yours!