Why is "don't you" pronounced "dontcha"?

Question

When I watch movies sometimes I feel the pronunciation for don't is not /dəʊnt/ or /doʊnt/, instead it's something similar to /doʊntʃ/. For instance here: Don't you see

I wonder is this something specific to American accent?

Answer 1

𝑇𝐿;𝐷𝑅

In General American English, don't is pronounced /doʊnt/ while in Southern Standard British English, it's pronounced /dəʊnt/.

In don't you, the /t/ of don't and /j/ of you coalesce to /tʃ/. The process is called assimilation.

𝐸𝑥𝑝𝑙𝑎𝑛𝑎𝑡𝑖𝑜𝑛

Assimilation makes nearby sounds more similar to each other. The kind of assimilation in don't you is called coalescent assimilation.

When /j/ comes right after /t/, there's a tendency to assimilate them to /t͡ʃ/. The /t/ is normally articulated at the ridge right behind the top teeth (alveolar ridge), but when it comes before a /j/ (which is articulated further back in the mouth—at the hard palate), it's usually pronounced /t͡ʃ/. What happens here is that the /t/ is articulated further back in the mouth in anticipation of the following /j/, so it becomes /t͡ʃ/ i.e. they coalesce to /t͡ʃ/.

The following sounds often coalesce:

• /t/ and /j/ coalesce to /t͡ʃ/ (as in posthumous)
• /d/ and /j/ coalesce to /d͡ʒ/ (as in education)
• /s/ and /j/ coalesce to /ʃ/ (bless you is sometimes pronounced bleshoo)
• /z/ and /j/ coalesce to /ʒ/ (as in vision)

You might have noticed that in informal situations (mostly in chatting platforms), most people write contractions such as dontcha, whatcha, gotcha etc. These are the phonetic spellings of the assimilated forms.

• dontcha → don't + you
• whatcha → what + you
• gotcha → got + you
• betcha → bet + you

Similarly, 'did you' is often pronounced as /dɪdʒjuː/ because /d/ and /j/ assimilate to /d͡ʒ/.

I wonder is this something specific to American accent?

No. It's not restricted to American English.

Answer 2

You are hearing the merging of the /t/ with the /j/ (or "y") of you.

If spoken as separate words you would hear.

don't. you. = /dəʊnt/ /ju:/

But normally these are run together and blend to form something like

don'tyou = /dəʊntʃu:/ or even "dontcha" (similar to "gonna" or "wanna")

You can hear the same with other words ending in "t", "I want you to" can become "Iwanchuta" when spoken quickly.