AUDIO PROBLEM FACETIME

How do I solve this probleme of Audio with my facetime?

I have a I MAC 10.6.8 2 GHz Intel Core 2 Duo, 4 GB 667 MHz SDRAM MAC

and the person I want to talk to has a

Mac 8GB 1600 MHz DDR3, 3.1 GHz Intel Core i7.

Can I fix this probleme?

Can you give me a check list of what needs to be check?