Here is a generic emergency checklist for a Boeing in a situation that may well be similar to what your Dad found himself involved in that I grabbed off the net.
It may give you an idea of what the pilots were doing. Keep in mind that this is after they have decided that there is actually a pressurisation problem.
[quote1 Don oxygen masks and set regulators to 100%.
2 Establish crew communications.
3 Pressurisation mode selector . . . . . . . . . . . . MAN
4 Outflow VALVE switch . . . . . . . . . . Hold in CLOSE until the outflow VALVE indication shows fully closed
5 If cabin altitude is not controllable:
Passenger signs . . . . . . . . . . . . . . . . . . . . ON
If the cabin altitude exceeds or is expected to exceed 14,000ft:
PASS OXYGEN switch . . . . . . . . . . . . O][/quote]
After doing that and deciding an emergency descent is in order;
Announce the emergency descent.
2 Passenger signs . . . . . . . . . . . . . . . . . . . . . . ON
3 Without delay, descend to the lowest safe altitude or 10,000ft, whichever is higher.
4 ENGINE START switches (both) . . . . . . . . . CONT
5 Thrust levers (both) . . . . . . . . . Reduce thrust to minimum or as needed for anti-ice
6 Speedbrake . . . . . . . . . . . . . . . .FLIGHT DETENT
- - - - - - - - - - - - - - - - - - - - - - -
The bit that says " announce the emergency descent" isn't left up to the whim of the Captain as to what he or she says, it will be something along the lines of .....funnily enough " emergency descent emergency descent emergency descent" . The announce doesn't just apply to the passengers and crew, while that is being done the other pilot will be announcing to ATC and other aircraft.
One reason that it may sound like the Captain is " screaming " the announcement is that earlier on you would have noticed that oxygen masks were donned, the mic is enclosed and close to the mouth and can have this effect when combined with a heart rate of 150bmp
This may or may not be what occurred on your Dads flight but I thought it might help you see the order of priority that things are generally carried out in and make it a bit more obvious that adding in the odd " Chuck Yeager PA " can disturb the flow of things.
Hope that helps.