Science Fair Project Encyclopedia
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.
They are normally detachable, using a jack plug. Typical products to which they are attached include the walkman, mobile phone, CD player, digital audio player (MP3 player), and personal computer. Some headphone units are self-contained, incorporating a radio receiver. Other headphones are cordless, using radio (e.g. analogue FM, digital bluetooth, WiFi) 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 protect others. They are also used to exclude external sounds, particularly in sound recording studios and in noisy environments.
Types of headphones
These type of headphones have pads that go around the ears, usually very large and very comfortable. They usually have a laid-back sound and a large soundstage while losing much intimacy. Examples include: AKG K501, Sennheisers HD650s, Beyerdynamic DT880s.
These type of headphones have pads that go on top of the ears, usually producing a closer and tighter sound than circumaural phones. Examples include: Bose QC2, Grado SR-80.
Canalphones (also known as "in-ear headphones") are placed inside the ear canal, positioning them closer to the eardrum than other types of headphones. They have excellent isolation quality (up to 24 dbs) because they act as earplugs. Isolation from canalphones is generally superior to that provided by active noise cancellation mechanisms. Canalphones are a relatively new type of headphone, based on the technology used in hearing aids. High-end canalphones are considered to be reference quality . Examples include: Sensaphonics 2X, Shure E2c, and Etymotic Research ER-4p.
Earbuds 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. The distinctive white headphones included with the iPod are earbuds.
The closer the driver is to the eardrum, the more easily it can impair hearing.
Dynamic drivers use magnetic material attached to a diaphragm that oscillates back and forth. This is the most common type of driver used in headphones.
A thin mylar sheet is between two metal plates and a charge imbalance on the plates vibrates the mylar sheet, producing a diaphragm. These are usually much better quality due to the fact that electrostatic diaphragms have a faster "attack" or speed.
Usually used only in canalphones such as sensaphonics.
Open headphones (sometimes marketed as "open air" headphones) have an open grille on the back of the driver, allowing the sound to vent freely. This usually makes open headphones sound better than closed ones of the same cost range. They also expose the user to more outside sound in cases where that is desirable.
Closed headphones are just that, closed backing. Usually these are used where isolation is preferred over sound quality.
Apparatus used to secure the earpiece on the ear
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 mess up ones hair like an over-the-head headband does, and can be worn with hats, etc. This now-popular style was newly popularized recently by a particularly trendsetting pair by Sony.
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.
Many earbuds and canalphones do not need or have anything to secure themselves inside the ear.
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.
Prominent manufacturers of headphones
- AKG Acoustics
- Etymotic Research
- GN Netcom / JABRA
- Koss Corporation
- Types of headphones
- Head-Fi high fidelity headphones discussion forum
- Headset Benefits
- Headwize: A Resource Site for Headphones and Headphone Listening
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