Actors Josh Radnor and Michael Weston pronounce shouldn't like "shunt" or wouldn't like "wunt". Is there a proper linguistic term for this pattern of pronunciation?
Book-writing [bʊk̚ˈɻʷʌɪʔn̩] versus real speech
What you’re seeing here is the simple reduction of weak syllables in casual connected English under fast speech rules, sometimes called allegro rules. It is perfectly common in all native speakers everywhere. These reduction processes are much too complicated and variable to describe here, but this is perfectly common to all native speakers everywhere.
What we write does not reflect what we say. Even at its best, our alphabet is a phonemic system not a phonetic representation. The actual phonetics — the sounds — vary substantially in different regions, registers, and phrase environments.
When we call something we write with an apostrophe a “contraction”, we are acknowledging that this shortening-up process occurs, but even with written contractions, their modified spelling again “fails” to represent what is actually said.
I use scare quotes around the word fails because the only failure here is the failure to understand the difference between standardized written representation and actual phonetics.
Here are just a few samples of the actual sorts of sounds one can often hear under fast speech rules:
- isn’t [ɪ̃ˀ]
- aren’t [ɐ̃˞ˀ]
- can’t [kʰæ̃ˀ]
- can’t’ve [ˈkʰæntəv], [ˈkʰænə]
- won’t [wõˀ]
- didn’t [dĩˀ]
- doesn’t [ˈdʌ̃ˀ]
- hasn’t [ˈhæzn̩ˀ], [hæʔ̃]
- hadn’t [ˈhæʔn̩ˀ]
- has to [ˈhæstə]
- have to [ˈhæftə]
- have to have [ˈhæftəv]
- has to have [ˈhæstəv]
- you would have had to have asked him [ˌjuɾəˌhæˀtəˈvæstm̩]
- mustn’t [ˈmʌsn̩ˀ]
- couldn’t [kʰʊ̃ˀ]
- shouldn’t [ʃʊ̃ˀ]
- wouldn’t [wʊ̃ˀ]
- could’ve [ˈkʰʊdəv], [ˈkʰʊdə], [ˈkʰʊ̃ɾə], [ˈkʰʊ̃ʔə]
- coudn’t’ve [ˈkʰʊ̃ˀnəv][, ˈkʰʊ̃ˀnə]
- shoudln’t’ve [ˈʃʊ̃ˀnəʔ]
- wouldn’t’ve [ˈwʊ̃ˀnəʔ]
- might’ve [ˈmɑɪʔə]
- might’nt’ve [ˈmɑɪʔnə]
- must’ve [ˈmʌstə]
- needn’t [ˈnĩˀ]
- needn’t’ve [ˈnĩʔnə]
- I’m not [n͡mɔʔ], [n͡mɑʔ]
- if he’d’ve [ɨˈfidəˀ], [ˈfidəˀ], [ˈfiɾəˀ]
- we’d’ve [ˈwidəˀ], [ˈwiɾəˀ]
- who’d’ve [ˈhudə], [ˈhʊdə], [ˈhuɾəˀ] [ˈhʊɾəˀ]
- ought to [ˈɔʔə], [ˈɔɾə]
- want to [ˈwʌnə], [ˈwɐnə], [ˈwɑ̃ʔə]
- going to [ˈgʌnə]
- going to have [ˈgʌnəv]
- he is going to have [ɨzˈgʌnəv]
There is nothing “sloppy” or wrong with any of those. It’s simply how native speakers regularly speak the English language in real life, not in book-writing [bʊk̚ˈɻʷʌɪʔn̩].
I'd say what you're talking about here is actually the glottal stop (https://en.wikipedia.org/wiki/Glottal_stop). The "d" doesn't just disappear; it's replaced with a shorter stoppage of airflow from the trachea. This makes the word faster to pronounce as the tip of your tongue doesn't have to hit the palate edge to pronounce the "d" but can simply press against the whole roof of your mouth to pronoune the "n" and move straight on to forward palate to hit that "t" (or even miss out the "t" too if the next word begins with a consonant).
I think syncope is correct although of course another word to explain it is slovenly. I would have been berated by my 'always speak correctly' mother for being so lazy and would never have been allowed to get away with speaking like this. However, being older I do now realise that this is how language evolves and there is no right or wrong when it comes to speaking English no matter how much it jars at the time.