This episode is called 'Honking Nose'. After Matthew and Sweep have come home after going through town pressing people's noses. Listen to what Matthew is saying. He says 'No-one could actually hear him!' (Sweep's honking nose and ringing ears). But everyone in town could hear it, except one!

A serious misjudgement because what should have happened was... the sound of the nose and ears are obviously sound effects, so the kids should have said 'I can't hear him.' But they said they did by mistake! Also, Matthew's scene at the house afterwards was done before they went out.