Headphones (or early headphones for phones and radios) are a pair of small listening devices designed to be worn over or around the user's ears. They are electroacoustic transducers that convert electrical signals into corresponding sounds in the user's ears. The headset is designed so that a single user can listen to the audio source privately. Compared with the loudspeaker, the loudspeaker can transmit sound to the open air, which can be heard by anyone nearby. Headphones are also called loudspeakers, headphones, or cans. Earrings and earphones are held in place over the head using straps. Another type, known as earplugs or earphones, consists of individual units that are inserted into the user's ear canal. In telecommunications, headphones are a combination of headphones and microphones. The headset can be connected to a signal source, such as an audio amplifier, radio, CD player, portable media player, mobile phone, video game machine or electronic instrument, directly using a wire or using wireless technology (such as Bluetooth or FM radio). The first headphones were developed in the late 1800s from telephone receivers for telephone operators to keep their hands free. At first, the audio quality was medium, and a step forward was the invention of high fidelity headphones.

Headphones have many different audio reproduction quality functions. Headphones designed for phones are often unable to reproduce sound with high fidelity, which is designed for audiophiles to listen to music. Headphones that use a cable usually have a 1 / 4-inch (6.35 mm) or 1 / 8-inch (3.5 mm) telephone jack to plug the headset into the audio source. Some stereo earplugs are wireless, using Bluetooth connections to transmit audio signals over radio waves from source devices such as mobile phones and digital players. [4] In recent years, due to the popularity of wireless devices, people are using headphones more and more in public places such as sidewalks, grocery stores and public transportation. People also use headphones in a variety of professional environments, such as audio engineers mixing sounds in live concerts or recordings and DJs, and they use headphones to remind them of the next song they're going to play, whereas listeners, aircraft pilots and call center staff don't. The latter two types of employees use headphones with integrated microphones.