A little bit of filtering and amplification would surely give you the breathing.
Correct and when analyzing sound a spectrum analyzer give a 'visual picture' of frequencies of interest.
Example:
Cockpit background noise will have it's own frequency plot.
Aural alarms will have it's own frequency plot.
Electrical seat movement will have it's own frequency plot.
Someone banging cockpit will have own plot.
Breathing thru Full face mask will have it's own frequency plot.
A spectrum analyzer can differentiate all these.