/z/ → /ʒ or ʃ/
The voiced fricative alveolar /z/ becomes a voiced fricative post-alveolar /ʒ/ when followed by /j/. In theory, this should happen in the same way when the next sound is the voiceless post-alveolar /ʃ/, and this is what most books about English pronunciation say. However, in practice, that sound is devoiced by the proximity of the voiceless /ʃ/ -remember what we said about the devoicing of final consonants-, so it turns into a /ʃ/ as well. The sequence /z/ + /ʃ/, then, is very often pronounced /ʃ ʃ/, which, unlike the cases we have studied so far, also implies a change in voicing .
/z/ (followed by /j/) becomes /ʒ/
As we saw in the previous article, sometimes the sound /j/ can still be heard, so the resulting sequence would be /ʒ j/. In other cases, however, the /j/ is not heard because it has been completely assimilated into the new sound.
/z/ (followed by /ʃ/) becomes /ʃ/
These shoes need some polishing.
I don’t like those quiz shows.
And here are some examples:
Today, as you’re asking me today, and it could be different next Tuesday, I’m going to say The Beatles, just because I can’t think of anyone better (Martin Freeman, BBC3).
It surprises me how few people seem to do it because you learn about aviation and history (Cambridge Advanced test).
Especially shoes you can’t walk in. I would say that’s quite a common feature (Sophie Woodward, BBC4).
In this recording you can see the assimilation case where there is a change of both place of articulation and voicing (/z/ becoming /ʃ/):
Every week over 6.600 people vacation aboard the world’s largest cruise ship (advertisement for a cruise ship). |ˈkruːz ʃɪp| → |ˈkruːʃ ʃɪp|