What is the main principle of the speaker

The speaker is capable of producing sound waves through the piston movement of the diaphragm. The piston movement is formed by the mutual inductance of the voice coil and the driving magnet. In the speaker unit with permanent magnet and coil: permanent magnet by a yoke in the annular air gap magnetic circuit produces a magnetic field, and loudspeaker diaphragm connected to the voice coil insertion annular air gap. The voice coil is a cylindrical object which is made of a thin metal wire, and the current signal is output from the amplifier.      

When the sound is in the form of a current through the voice coil, according to the current intensity and frequency of the corresponding changes in the electromagnetic field, the magnetic field direction according to Faraday's right hand law. The magnetic force of the electric ring changes with the change of the electric current, and the interaction between the permanent magnet and the permanent magnet is in vibration, which drives the diaphragm to make the piston movement. The effect of phase plug for the ultimate goal of all sound system is to faithfully restore the original appearance of the sound source. Therefore any form of sound is actually a distortion. Therefore, various methods should be adopted to avoid such distortion.