Why can't I be heard on FaceTime calls?

I've had my iPad mini for several months now and I use it once in a while primarily for Netflix. It is cracked in the upper right corner pretty severely about an inch to from the camera diagonally to about 3 inches from the top. I don't know if that could be a reason. Also i have no case on it. Water damage could be a possibility since I have had it in the rain, but I can still hear Netflix and YouTube etc. Except. I can't hear videos that I record from my camera. So what's broken about it, how do you think it broke, and can it be fixed? Thanks
Added (1). When I did have it in the rain, it was only in the rain for a few seconds from the time it took to get from my car to my house.

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