Place it at the exact cut where you first appear on screen, then follow it with the Darth Vader No sound for the reaction shot, or end the sequence there if the entrance is the whole gag.
關於此聲音
This is Ewan McGregor as Obi-Wan Kenobi saying 'Hello there' in a bright, assured voice, made louder than the film version and lasting under a second. It feels cheerful and cheekily grand, turning a normal arrival into a playful reveal. It comes from Star Wars: Revenge of the Sith, during his surprise drop-in on General Grievous.