HI~ Would you help me how to say this naturally please?

A: Hello! Hello! No body here? Hello!

B: Hi, You donít have to call loudly so many times, call once enough.

A: Oh, sorry. I thought you didnít here.
Or, I though you couldnít here.
Or, I though you havenít heard.

B: I was doing some other things. So, how can I help you?