Pardon me?

What do you say in Japanese when you can't catch what the other person is saying? In English, we would say "Pardon me?" Is there an equivalent Japanese expression?

I would recommend you to say;

Sumimasen, mouichido onegaisimasu.

or

Sumimasen, mouichudo ittekudasai.

"Excuse me, please say that again."

sumimasen, mou ichido yukkuri itte kudasai.
Excuse me. Please say it again slowly.

Assuming you are a native speaker of Japanese as well, do you still say "mou ichido onegaishimasu" or "mou ichido itte kudasai"?

Allow me to give some context:

Both the speaker and listener are native speaker of Japanese.

Scenario 1 - The listener is a friend of yours. Both of you were having a chat and in the middle of the conversation, your friend said something that you did not manage to catch.

Scenario 2 - Same as above except that the listener is your friend's parent.

informally as goes up
1 e? (huh?)
2 mokkai itte? / (what?)
3 mokkai onegai (say that again?)
4 mou ikkai onegai shimasu (please, say that again? / pardon?)
5 sumimasen, mou ichido onegai shimasu (please, say that again?)
6 sumimasen ga, mou ikkai itte itadake naide syouka?
(i beg your pardon?)

for friends : 1-3
for parents,teachers,boss : 4-5 sometimes 6

WHat are the genders? From a male to a male, a female to a female, or both the same genders?