The helmet also had tubes running in from the back so that the designer could make the 'eyebrows,' feelers, and 'nose' move using pumped air. But whenever he would make them move, all I could hear was pssshhhh pshhh pssshhhhh.
There were a couple of times when the director would give me instructions while the designer was testing the moving parts. So I couldn't hear a word the director was saying or see what he was indicating, but I could tell he was telling me something important. I would have to wait for the psshhhing sounds to stop, so that I could say to the director, "Sorry, could you repeat that for me?"