The sequence with which these 5 knocks were recorded is important, "Knock, knock knock, knock knock", this coincided with the discharge of Woodcocks entry into the main kitchen, the shooting of Sheila, and finishing off of Ralph Bamber:-
"KNOCK" Sheila pulls muzzle of Woodcocks weapon into her throat, as though she wants him to shoot her...
"KNOCK, KNOCK" Woodcock shoots Ralph in top / back of skull..
"KNOCK, KNOCK" Woodcock shoots Ralph in top / back of skull..