"You'd have to be on the aircraft and hear the RA to know for sure"
We as pilots are of course trained to respond to RA's. We also are aware a response may cause us to deviate from altitude and the relative comfort that an assigned altitude provides. It only takes one guy to handfly the escape maneuver, the other is taught to immediately advise ATC so they are in the loop. Many times a RA is not a great surprise. Watching the TCAS we see someone heading towards us, it turn to a TA and finally a RA. This allows time to think about impending requirements such as ATC notification.