Headphones
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Wikipedia-Article "Headphones"
Headphones (also known as earphones, stereophones, headsets, or the slang term cans) are a pair of transducers that receive an electrical signal from a media player or receiver and use speakers placed in close proximity to the ears (hence the name earphone) to convert the signal into audible sound waves.
Headphones date from the beginnings of the history of the telephone and the radio. The weak electrical signals of the early instruments were enough to operate only headphones audibly.
They are normally detachable, using a jack plug. Typical products to which they are attached include the walkman, mobile phone, CD player, Minidisc player, digital audio player (MP3 player), and personal computer. Headphones can also be used with full-size stereo components. Some headphone units are self-contained, incorporating a radio receiver. Other headphones are cordless, using radio (for example analogue FM, digital bluetooth, Wi-Fi) or infrared signals to communicate with a "base" unit.
Headphones may be used to prevent other people from hearing the sound either for privacy or to prevent disturbance, as in listening in a public library. They are also used to exclude external sounds, particularly in sound recording studios and in noisy environments. Another advantage of headphones over conventional speakers is that the listener experiences total stereo-separation with no mixing of the left and right channels, helping them pinpoint the 'location' of sounds with much greater accuracy. This is of special relevance to videogames that use 3D positional audio, allowing players to better judge the position of an offscreen sound (such as the footsteps of an opponent). A good example of this 3D positioning in action is the game Battlefield 2 for PC. Many players find headphones extremely useful as far as listening for enemies firing around their avatar, or someone sneaking behind it for a quick knife-kill.
Headphones generally use a 3.5 mm "mini pin" jack, and often are supplied with a 3.5 mm to 1/4" jack adapter (some adapters screw onto the end of the cable, while others secure by friction or mechanical coupling). Many higher-end headphones are directly terminated with a 1/4" jack, which are more durable than a 3.5 mm jack.
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Types of headphones
In descending order of size:
Circumaural
These type of headphones have pads that go around the ears, usually very large and very comfortable. This is the type typically used in recording studios. Examples include: AKG K501, Audio-Technica ATH-A900, Beyerdynamic DT880, Sennheiser HD650, Bose Tri-Port Headphones, and Sony MDR-SA5000.
Supra-aural
These type of headphones have pads that go on top of the ears. They were commonly bundled with personal stereos during the 1980s. Examples include: Grado SR-60, Koss Sportapro, Sennheiser PX-200.
Earbuds/Earphones
Earbuds (American English) or Earphones (British English) are small headphones that are placed directly outside of the ear canal, but without fully enveloping it. Earbuds are generally inexpensive and are favored for their portability and convenience. However, due to their inability to provide isolation, they are not capable of delivering the precision and range of sound offered by many full-sized headphones and canalphones.
During the 1990s, they became the most common type bundled with personal stereos. For example, the distinctive white headphones included with the iPod are earbuds.
IEMs/Canalphones
Canalphones are earbuds that sit directly inside the ear canal. They offer extreme portablity, sound isolation, and (in many cases) amazing sound. These are a favorite of audiophiles on the go.
There are two main types of IEMs/Canalphones--universal, and custom. Universal IEMs are exactly that--universal. They have a nozzle that protrudes from the tip of the earphone, on which the user can place several different sizes of "sleeves" (which are commonly made out of rubber, soft plastic, and foam). Several prominent universal canalphone manufacturers are Etymotic, Panasonic, Shure, Sony, Ultimate Ears, and Westone. Custom IEMs, however, are engineered to fit only one person. The user must go to an audiologist to get ear canal impressions made. The user will then ship these ear impressions to the manufacturer, who will then make custom canalphones with the exact same shape. The manufacturer will often allow custom engraving of the earphones (with initials, perhaps), and usually will have a large pallete of colors for the buyer to choose from. Custom canalphones cost much more than universal canalphones due to the work required to make the earphone tip match the ear impression. The three large custom IEM manufacturers are Sensaphonics, Ultimate Ears, and Westone.
Driver types
Dynamic
The dynamic driver is the most common type used in headphones. This principle consists of a magnetic element attached to a thin diaphragm, which is often a paper material. The diaphragm is actuated by a voice coil, oscillating it and inducing vibrations into the air producing sound. The magnetic element in headphones are often composed of ferrite, mostly in lower-end or very cheap headphones. Stronger neodymium magnets are used in most modern headphones.
Electrostatic
A thin, electrostatically charged diaphram (typically a coated mylar membrane), is suspended between two perforated metal plates (electrodes). The electrical sound signal is applied to the electrodes creating an electrical field; depending on the polarity of the this field, the membrane is drawn towards one of the plates. Air is forced through the perforations; combined with a continuously changing electrical signal oscillating the membrane, a soundwave is generated.
Typically electrostatic headphones are more expensive than dynamic, and are relatively rare. In addition, a special amplifier is required to amplify the signal to oscillate the membrane, which often requires electrical potentials in the range of 100 to 1000 Volts.
Examples of electrostatic headphones are the Stax SR-007 Omega II, and the Sennheiser HE90 "Orpheus".
Balanced armature
Usually used only in canalphones (due to their diminutive size), such as Etymotic, Shure!, and Sensaphonics.
Backing type
Open
Open headphones (sometimes marketed as "open air" headphones) have an open grille on the back of the driver, exposing the driver to the outside, and allowing the soundwaves to propagate away from the ear freely. This backing type does not isolate the listener from outside sounds; in addition, sound through open headphones can be easily heard by others in the vincinity of the user (not always a desirabile quality).
Examples of open headphones: AKG K-501, Grado RS-1, Sennheiser HD-650.
Closed
Closed headphones have a sealed backing, which attenuates soundwaves propagating in the direction away from the ear. As a result, listeners away from the headphones cannot hear the produced sound easily. In addition, extra-soundwaves are attenuated due to the sealed backing, providing a level of isolation to the listener (typically a 10dB decrease in outside sounds).
Examples of closed headphones: AKG K271S, Audio Technica ATH-A900, Sennheiser HD-280 Pro, Sony MDR-CD3000.
Apparatus used to secure the earpiece on the ear
Headband
A headband goes over the head. It is usually used with circumaural and supra-aural headphones, but is sometimes used with earbuds or canalphones.
Behind the neck
Behind the neck go behind the neck, and are usually used in portable supra-aural headphones. They do not disturb one's hair like an over-the-head headband does, and can be worn with hats, etc. This now-common style was popularized recently by a particularly trendsetting pair by Sony.
Clip
A clip secures the earpiece with a clip that goes behind the outer ear. Usually used with earbuds, but also sometimes used with supra-aural headphones or canalphones.
None
Many earbuds and canalphones do not need or have anything to secure themselves inside the ear.
Dangers
Using headphones at a sufficiently high volume level causes temporary or permanent hearing impairment or deafness. Other risks arise from the reduced awareness of external sounds — some jurisdictions regulate the use of headphones while driving vehicles. Also, most European countries have imposed high penalties since 2002 on drivers not using a headset while operating a mobile phone in a car, to ensure that drivers keep their hands on the vehicle's controls. It should be noted, however, that the usage of canalphones (which sit directly in the ear canal, much as earplugs do) is actually safer than other types of headphones. The reason for this is that much of the the external noise which is usually heard while using earphones/headphones is blocked out by canalphones, therefore allowing the user to listen at lower volumes without having to turn up the listening device (possibly to unsafe levels) to compete with background noise.
Benefits
Headphones can have an ergonomic benefit over the traditional handset at your office desk. They save space and many new models are wireless. They also allow telecenter agents to maintain good posture instead of tilting their head sideways to cradle a headset.
Prominent manufacturers of headphones
- Acoustic Research
- Aiwa
- AKG Acoustics
- Apple
- Audio-Technica
- Behringer
- Beyerdynamic
- Bose
- Coby Electronics
- Denon Electronics
- Etymotic Research
- Future Sonics Incorporated
- GN Netcom / JABRA
- Grado
- Koss Corporation
- Logitech
- Panasonic
- Philips
- Pioneer Electronics
- Plantronics
- RCA
- Sennheiser
- Shure
- Sony
- Stanton
- STAX
- Technics
- Ultimate Ears
- Ultrasone
- Victor Company of Japan, Limited
- Westone Laboratories
See also
External links
- The Audio Circuit - Information on and user reviews of loudspeakers, headphones, amplifiers, and playback equipment
- Types of Headphones
- Head-Fi: High Fidelity Headphones Discussion Forums
- Headphone Gallery & Archive - Database of Headphone Specifications and Images
- Headset Benefits
- Headwize: A Resource Site for Headphones and Headphone Listening
- MVHeadphones: Noise Isolation vs. Noise Cancelation