In this game of transformations that we make when working with audio, the last link in the chain is the speaker. In some places they are also known as horns or speakers, because “parlan”, which is the same as talking.
If sound vibrations (acoustic signals) are transformed with the microphone into electricity (electrical signals), the speaker does the reverse work: it transforms electricity into sound. It is easy to deduce, then, that the operation of both devices is very similar. The two are built using the principles of electromagnetism. The loudspeaker is merely a coil around a magnet which, upon receiving an electric current, moves a membrane that generates sound waves.
The speakers are similar to microphones both in operation and under construction. There are dynamic speakers, such as the one just explained, and other electrostatic (condenser) or piezoelectric models that are less common.