Sound generation by a loudspeaker. The alternating current being applied to the loudspeaker causes the mechanical oscillation of a coil connected with cone of the loudspeaker. As a result of this oscillation some regions of the air turn out to be compressed, while the other regions are rarefied. The regions with excessive pressure are propagating in the space in the form of longitudinal waves. When such a wave reaches the ear, it forces the eardrum to be oscillated and we hear the sound.