The heating of the earphones is caused by the vibration of the earphone speakers. Headphone speakers work by converting electrical signals into acoustic signals, generating heat in the process. In addition, the headphone speaker also generates electricity when it is working, and the current also generates heat. This heat builds up and heats up the headphones. Hot earphones can also cause hot ears, because the heat emitted by the earphone speakers will be transmitted to the skin of the ear, making the skin temperature of the ear.