When they were falling with constant descent rate, about 10.000 ft/min, they cannot find it by their senses. They could discovere it by the instruments (altimeter, variometer) in combination with their nose up attitude (by artifical horizon). If they had an AoA meter, the could discovere it seeing extreme angle of attack.
At least ....
At the speed with which they came down .. they would certainly have some effect at the eardrums due to pressure difference ... (hurt feeling)
Even at reasonable rate of descent you feel this (even if cabin pressurised)