An unfurnished classroom having bare walls, a cement floor, and a high concrete ceiling often sounds "echoey", while the same room becomes much quieter after it is furnished with curtains, wall-boards, and cushioned chairs.
(i) Explain why stronger echoes are heard in the empty classroom than in the furnished classroom.
(ii) Describe the role played by soft furnishings such as thick curtains in reducing the persistence of sound inside the room.