You know that sound reaches our ears in the form of waves.These waves require certain medium for their propagation.

 

Marconi was inventor of radio waves.

 

On the other hand light is also a form of waves, but it does not required any medium for its propagation.Light can pass through vacuum as well. Such waves are called electromagnetic waves.Heat,Light,x-rays etc.,

Radio system

 Sound waves cannot travel through long distance. Moreover their speed is very low, that is about  340 m/s .To carry sound waves to long distance , radio waves are used. For this purpose radio station are built .

At radio station, Micro Phone converts sound waves into electric signal .An electric circuit produce radio waves of some particular frequency .These are then mixed with sound signal.These carrier waves are transmitted all around through  a transmitter antenna.