How to say what did you say? in Japanese

1．Nanto ossyaimashitaka？　なんとおっしゃいましたか？

This phrase is the most polite words for asking people to show that you couldn’t catch the phrase and ask them to repeat it. This could be used in any business situation. For example, you don’t have to consider your position when you use this phrase like you can say this words for from bigwigs to children. This could be also used for someone you respect. So, if you are confused with which one should you use, this phrase will definitely help you.

2．Nanto iimashitaka? なんといいましたか？　

This is lower level of けいご（Keigo, honorific expression）than above one (Nanto Ossyaimashitaka?), however, this could be also used in business situations in a gray area. This words wouldn’t be used by native Japanese speaker personally. So I don’t recommend using this words.

3. Nante? なんて？

This word is most popular and most casual phrase that could be used in any situations besides business situations. So, this one is so useful, but you should watch out your pronunciation. If you say this with angry voice with angry face, your friends would be easily got mad at you. Be careful.

4．Ha？　　　は？

This one is used when you are pissed off or when you are kidding someone. It is definitely not the same as Hah? in English. Compared to English phrase Hah?, Japanese one has some meanings like being mad at you, laughing at you or astonishing.