I wonder how I should reply if someone said something to me, and I haven't made out some words. I fluctuate between these two options:
- I'm sorry. I haven't heard what you've just said.
- I'm sorry. I didn't hear what you said.
The first answer seems more grammatically correct. However, the second answer sounds better to me, and I'd use it in a real conversation. Or probably both of them are fine?