How sound is transmitted to speakers?

A microphone is a transducer that vibrates when in the presence of sound. These vibrations are converted into fluctuations in voltage that are transmitted to an amplifier. The amp then can increase the received voltage and transmit again via voltage fluctuations to a speaker which is also a transducer. In this case the electric signals vibrate a coil that in turn vibrates a membrane of some type creating sound waves by causing molecules in the air to vibrate.