Headphones (or head-phones in the early days of telephony and radio) are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound.
Headphones are made in a range of different audio reproduction quality capabilities. Headsets designed for telephone use typically cannot reproduce sound with the of expensive units designed for music listening by . Headphones that use cables typically have either a 1/4 inch (6.35mm) or 1/8 inch (3.5mm) for plugging the headphones into the audio source. Some stereo earbuds are wireless, using connectivity to transmit the audio signal by radio waves from source devices like cellphones and digital players.Due to the spread of wireless devices in recent years headphones are increasingly used by people in public places such as sidewalks, grocery stores, and public transit. Headphones are also used by people in various professional contexts, such as mixing sound for live concerts or and , who use headphones to up the next song without the audience hearing, aircraft pilots and employees. The latter two types of employees use headphones with an integrated microphone.