"Sorry" or "I'm sorry" to ask people to repeat themselves? Are both acceptable?

Yeah, both’s fine. Just make sure you add an upward inflection like a question. “Sorry?” “Excuse me?” “I’m sorry, one more time?” “Pardon?” “Sorry, I didn’t catch that.” And so on.

Both are equally acceptable. You can also say "Excuse me?" or "Pardon?"

I am a native English speaker from the UK originally, lived in Australia for many years. It's marginal, but 'I'm sorry' with a leaning in gesture covers most bases when you want to be polite. A plain 'Sorry?' can and probably should be interpreted as somewhat passive aggressive in a conversation. But it's very nuanced. If you inadvertently (say) bump into a stranger while running for a bus, 'Sorry' is fine.

You can use "sorry" even for "excuse me". It's simple and straight.

I saw this clip , I believe the guy has a strong Scottish accent and the other gentleman said sorry twice. [https://www.youtube.com/watch?v=I4k8dR04TzA](https://www.youtube.com/watch?v=I4k8dR04TzA)

Yes. Master the other uses, and you’ll reach peak English! 🏴󠁧󠁢󠁥󠁮󠁧󠁿

In Ireland people use plain and simple: "Say it again!" No sorries, pardons or other euphemisms.

Yes both are acceptable and interchangeable.

https://m.youtube.com/watch?v=gsuuA7_uQ8U ;)

Both work but maybe sorry would sound better for casual conversation

Either works but a bit casual in my opinion, especially just "sorry" because a lot will depend on your tone of voice. A charming Brit can get away with it in any situations however. You can never go wrong with a polite "I beg your pardon". It's got a built-in formality but works even in a fairly casual conversations. Just shows good manners.

Both "Sorry?" and "I'm sorry?" work when asking someone to repeat themselves. "Sorry?" is slightly more casual and common in everyday conversation (e.g., "Sorry? Could you say that again?"). "I'm sorry?" adds a tiny bit of formality but is equally acceptable (e.g., "I'm sorry? I didn’t catch that"). Neither is wrong—use whichever feels natural. In some regions, "Pardon?" or "Excuse me?" might also pop up, but "Sorry" variations are universally understood.