It is not uncommon to see people of all ages walking along the street humming, perhaps dancing a little, or talking to this air. While some of them may be in need of psychiatric help, the overwhelming majority of them are listening to music through headphones.
The idea of delivering auditory material directly to the ears of a listener via a device over or in the ears, is not new. In fact, in the early days of sound transmission they were the only way to pick up the sound. The first headphones – or personal receivers - were made in 1910 by one Nathaniel Baldwin, who apparently made them in his kitchen and managed to market them to the Navy of the United States. Over the years the sensitivity of these receivers has increased hugely, and the Navy, among others, is able to pick up the subtlest sounds, as shown in the "The Hunt for Red October".
In many cases, the headphones are combined with a personal microphone in which case the apparatus is known as a headset. The headset is normally attached by wires to the audio source. It is used by radio operators, telephonists, call centre workers, or anyone else who spends a lot of time communicating with others at a distance.
Headphones by themselves have been used for the revolutionary Walkman and its successor, the Discman to take music out of the house, and the current mp3-style players. Sometimes earphones, in particular cordless headphones, are used with mobile phones when the hands are needed for other things. For a while this technology allowed drivers to speak on their phones in the car. In the United States, this sort of hands free device is still legal, but in the United Kingdom, the use of a mobile phone behind the wheel of a vehicle, even a stopped one, carries a heavy fine.
Headphones are, in effect, small loudspeakers held close to the ears in one of two ways - over-ears or in-ears. The former, also known as circumaural headphones, cover the whole ear, while the latter is a disc, or possibly a cone-shape, small enough to fit into the ear, in which case they are known as earbuds. These devices are very inexpensive, but have some drawbacks: they block out very little ambient noise, which may lead the user to turn up the volume to compensate for this noise. If another person can hear the music delivered by your earbuds, the volume is way too high. This level of volume is dangerous and can lead to hearing loss. Nevertheless, for the past 20 or so years earbuds have frequently been sold with a wide variety of personal music players.
Headphones can be used in many situations where the sound being delivered can interfere with others, or where environmental noise can interfere with the communications. For example, people who are hard of hearing can use headphones to augment the sound from the television.
Headphones are used by many professionals such as disc jockeys and sound engineers who use headphones to monitor signal sources and to eliminate feedback. In studio recordings and many stage musicals singers use headphones to listen to the orchestra or backing track.