Speaker does just the opposite task of the microphone. The speaker converts the electric signal of the microphone into the corresponding sound wave. Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive audio input from a device such as a computer or an audio receiver. This input may be either in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since sound waves are produced in analog form, digital speakers must first convert the digital input to an analog signal, then generate the sound waves.
Functions of the speaker: Most of the loudspeakers are moving coil loudspeaker. It has-
i) A cylindrical permanent magnet which produces a strong magnetic field.
ii) A small coil or wire-loop is suspended. This wire-loop can oscillate to and fro in the magnetic field.
iii) A paper cone remains attached with wire-loop. When the alternating current produced by the sound flows through the loop, the loop moves to and fro. For this reason, the paper cone is vibrated. As a result, the sound is produced.