Well having given birth to three kids, 2 by the Bradley Method and one by Lamaze, that actually turned back into Bradley, when I dilated from 4 to 10 in like 7 minutes.... my opinion is go for whatever works - if Amanda wants a natural childbirth, then thats what she should have and Masaki, you should just be there and do whatever she wants. I would do it again in a heartbeat, and never regretted one minute of it.
We have 4 Grandkids, and all 4 of them have ended up being born by C-section, for various reasons.
Oh yeah, forget the tape recorder, just forget it! Amanda, if he does that, then he can give birth to the next child and you can record it!!!! :D :D
Anyway - if the Natural Childbirth works and all is well, I highly recommend it, it was the best thing I ever did in my whole life.