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Headphones

Headphones (or "head-phones" in the early days of telephony and radio) are a pair of small loudspeakers that are designed to be held in place close to a user's ears. They are also known as earspeakers, earphones or, colloquiallycans. The alternate in-ear versions are known as earbuds or earphones. In the context of telecommunication, a headset is a combination of headphone and microphone. Headphones either have wires for connection to a signal source such as an audio amplifierradioCD playerportable media playermobile phonevideo game consoleselectronic musical instrument, or have a wireless device, which is used to pick up signal without using a cable.

The different types of headphones have different sound reproduction characteristics. Closed-back headphones, for example, are good at reproducing bass frequencies. Headphones that use cables typically have either a 1/4 inch jack or an 1/8 inch jack for plugging the headphones into the sound source.

Headphones may be used both with fixed equipment such as CD or DVD playershome theaterpersonal computers and with portable devices (e.g. digital audio player/mp3 player,mobile phone, etc.). Cordless headphones are not connected via a wire, receiving a radio or infrared signal encoded using a radio or infrared transmission link, like FMBluetooth orWi-Fi. These are powered receiver systems of which the headphone is only a component. Cordless headphones are used with events such as a Silent disco or Silent Gig.

In the professional audio sector, headphones are used in live situations by disc jockeys with a DJ mixer and sound engineers for monitoring signal sources. In radio studios, DJs use a pair of headphones when talking to the microphone while the speakers are turned off, to eliminateacoustic feedback and monitor their own voice. In studio recordings, musicians and singers use headphones to play along to a backing track. In the military, audio signals of many varieties are monitored using headphones.

Wired headphones are attached to an audio source. The most common connectors are 6.35 mm (¼″) and 3.5 mm phone connectors. The larger 6.35 mm connector tending to be found on fixed location home or professional equipment. Sony introduced the smaller, and now widely used, 3.5 mm "minijack" stereo connector in 1979, adapting the older monophonic 3.5 mm connector for use with its Walkman portable stereo tape player. The 3.5 mm connector remains the common connector for portable application today. Adapters are available for converting between 6.35 mm and 3.5 mm devices.

Headphone size can affect the balance between fidelity and portability. Generally, headphone form factors can be divided into four separate categories: circumauralsupra-aural,earbud, and in-ear.

Circumaural

Circumaural headphones (sometimes called full size headphones) have circular or ellipsoid earpads that encompass the ears. Because these headphones completely surround the ear, circumaural headphones can be designed to fully seal against the head to attenuate external noise. Because of their size, circumaural headphones can be heavy and there are some sets that weigh over 500 grams (1 lb). Ergonomic headband and earpad design is required to reduce discomfort resulting from weight.

Supra-aural

Supra-aural headphones have pads that press against the ears, rather than around them. They were commonly bundled with personal stereos during the 1980s. This type of headphone generally tends to be smaller and lighter than circumaural headphones, resulting in less attenuation of outside noise. Supra-aural headphones can also lead to discomfort due to the pressure on the ear as compared to circumaural headphones that sit around the ear. Comfort may vary due to the earcup material.

Open or closed back

Both circumaural and supra-aural headphones can be further differentiated by the type of earcups:

Open-back headphones have the back of the earcups open. This leaks more sound out of the headphone and also lets more ambient sounds into the headphone, but gives a more natural or speaker-like sound and more spacious "soundstage" - the perception of distance from the source.

Closed-back (or sealed) styles have the back of the earcups closed. They usually block some of the ambient noise, but have a smaller soundstage, giving the wearer a perception that the sound is coming from within their head. Closed-back headphones tend to be able to produce stronger low frequencies than open-back headphones.

Semi-open headphones, have a design that can be considered as a compromise between open-back headphones and closed-back headphones. This may imply that the result combines all the positive properties of both designs. Some believe the term "semi-open" is purely there for marketing purposes. While there is no exact definition for the term semi-open headphone, there are designs that can be considered as such. Where the open-back approach has hardly any measure to block sound at the outer side of the diaphragm, and the closed-back approach, really has a closed chamber at the outer side of the diaphragm, a semi-open headphone can have a chamber to block sound partially while leaving some sound through, via openings or vents.

Ear-fitting headphones

Earphones

Earphones (popularly called "earbuds" in recent years) are very small headphones that are fitted directly in the outer ear, facing but not inserted in the ear canal. Earphones are portable and convenient, but many people consider them to be uncomfortable and prone to falling out. They provide hardly any acoustic isolation and leave room for ambient noise to seep in; users may turn up the volume dangerously high to compensate, at the risk of causing hearing loss.[13][14] On the other hand, they let the user be better aware of their surroundings. Since the early days of the transistor radio, earphones have commonly been bundled with personal music devices. They are sold at times with foam pads for comfort.

In-ear headphones

In-ear headphones, also known as in-ear monitors (IEMs) or canalphones,[15] are small headphones with similar portability to earbuds which are inserted in the ear canal itself. IEMs are higher quality in-ear headphones and are used by audio engineers and musicians as well as audiophiles.

Because in-ear headphones engage the ear canal, they can be less prone to falling out and they block out much environmental noise. Lack of sound from the environment can be a problem when sound is a necessary cue for safety or other reasons, as when walking, driving, or riding near or in vehicular traffic.

Generic or custom fitting ear canal plugs are made from silicone rubber, elastomer, or foam. Custom in-ear headphones use castings of the ear canal to create custom-molded plugs that provide added comfort and noise isolation.[13]

Headset

A headset is a headphone combined with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. Among applications for headsets, besides telephone use, are aviation, theatre or television studio intercom systems, and console or PC gaming. Headsets are made with either a single-earpiece (mono) or a double-earpiece (mono to both ears or stereo). The microphone arm of headsets is either an external microphone type where the microphone is held in front of the user's mouth, or a voicetube type where the microphone is housed in the earpiece and speech reaches it by means of a hollow tube. Some headsets come in a choice of either behind-the-neck or no-headband design instead of the traditional over-the-head band.

Telephone headsets

Telephone headsets connect to a fixed-line telephone system. A telephone headset functions by replacing the handset of a telephone. Headsets for standard corded telephones are fitted with a standard 4P4C commonly called an RJ-9 connector. Headsets are also available with 2.5 mm jack sockets for many DECT phones and other applications. Cordless bluetooth headsets are available, and often used withmobile telephones. Headsets are widely used for telephone-intensive jobs, in particular by call centre workers. They are also used by anyone wishing to hold telephone conversations with both hands free.

For older models of telephones, the headset microphone impedance is different from that of the original handset, requiring a telephone amplifier for the telephone headset. A telephone amplifier provides basic pin-alignment similar to a telephone headset adaptor, but it also offers sound amplification for the microphone as well as the loudspeakers. Most models of telephone amplifiers offer volume control for loudspeaker as well as microphone, mute function and switching between headset and handset. Telephone amplifiers are powered by batteries or AC adaptors.

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