Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers that convert an electrical signal to a corresponding sound. Headphones allow a single user to listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. They can connect to a signal source such as an audio amplifier, radio, CD player, mobile phone, or computer, either directly using a cord or using wireless technology such as Bluetooth, DECT, or FM radio
. There are different types of headphones, including circumaural, supra-aural, earbuds, and bone conduction headphones
