"Cheia mea e mai mare decât a ta."

Translation: My key is bigger than yours.

[MihailHancu]

The audio is a bit unclear. You should be able to hear the "a" in "cheia" much clearer. Also, "mea" has its own accent, so it should be pronounced separately, not as an enclitic.

[PaulMinden]

Good ear!

[tatianandreeva]

I agree that in most auditing exercises it is quite hard to guess what was intended.