During a routine recording of an episode on Urban Legends (of all things!) the girls suddenly heard a loud strange knocking noise come from behind them! Each girl thought the other had made the noise, but neither one of them did it. I (Daddy) was in a totally different area of the house during the recording. I checked to see if anything had fallen down to make the noise, but nothing was out of place. It really sounds like something hit the background behind them! What do you think?