You can yell at them and they will not hear you as they become so focused on what they are seeing and feeling and stop hearing altogether.
In an incident similar to the one being discussed, a student could claim (and believe it sincerely) that you never told them to release the controls
Hearing is the first faculty to be lost when under stress. Seen it demonstrated when a PNF put out a mayday (rightly so) that the PF didn't hear as he was rather busy at the time.