What is characteristic of both sound waves and electromagnetic waves?

Sound waves are mechanical waves while electromagnetic waves are not. Thus, sound waves require a medium for propagation while electromagnetic waves do not. Sound waves are produced by mechanical vibrations and propagate through liquid, air and plasma as longitudinal waves. While electromagnetic waves are produced by accelerating or decelerating charged particles. It also contain a magnetic field. Because they are not mechanical waves, it can propagate through a vacuum as well as air, liquid, and solid.