(a) Why the stage of an auditorium has curved background, curtains, carpets and false ceiling? (b) The sound of a ringing bell inside a vacuum , chamber cannot be heard. Why?


(a) The curved surface is used to spread the sound in all directions. The curtains, carpets
and the false ceiling are used to prevent echo from occurring in the auditorium.
(b) This is because sound requires a medium to propagate.