Audio problem: In Engineering when Worf says "Ensign," Michael Dorn's lips don't move. (00:22:35)
Audio problem: After the offer of refreshments has been declined, Harmony says "I have been expecting you", but her mouth doesn't move.
Audio problem: We hear Reva's female member of his choir say "I have been expecting you", but her mouth doesn't move.
Answer: Yes. The doors to the holodecks can be locked when in use by anyone aboard the Enterprise so they couldn't be disturbed. However, high ranking officers like Captain Picard could override the doors as it's seen that overrides are in use even for the crews quarters. Even Barclay, when he's indulging in one of his fantasies could have the doors to the holodeck unlocked by an override code.