Are Mel Gibson tapes fake?

The tapes circulating on radaronline.com certainly sound like Gibson, but my impression since the time I heard them first is this........ His voice sounds muffled and staticy, but when she talks she sounds like she was recorded in high def digital audio in comparison. I suspect that under scrutiny they will find that her voice has been overdubbed onto a tape and that there are other fabrications to the tape to make it sound as if he said something that he did not. Every time I hear the tapes, I become more and more convinced that her voice is overdubbed. I mean she does not even raise her voice or get flustered in any way, and when someone is yelling and screaming, 99.9% of the population will lose decorum at some point and she sounds like she is having a casual conversation.