Ref the previous post about if CVR is able to pick up the normal sound of a person breathing
I have spend close to 10.000 hrs as a captain on an A320, and I have never been able to hear my colleagues breathing. Not even through Intercom, when he/her wore a headset.
The CVR microphone would also not be able to pick up normal breathing. You will know if you have spend time in an A320. And there was even more noise on this MMO/VMO descent from aerodynamic noise.