headphones for other uses see headphones disambiguation headphones on a stand headphones or headphones in the early days of telephony and radio are a pair of small loudspeaker drivers worn on or around the head over a users ears they are electroacoustic transducers which convert an electrical signal to a corresponding sound headphones let a single user listen to an audio source privately in contrast to a loudspeaker which emits sound into the open air for anyone nearby to hear headphones are also known as earspeakers earphones headphones are made in a range of different audio reproduction quality capabilities headsets designed for telephone use typically cannot reproduce sound with the high fidelity of expensive units designed for music listening by audiophiles headphones that use cables typically have either a 14 inch 635mm or 18 inch 35mm phone jack for plugging the headphones into the audio source some stereo earbuds are wireless using bluetooth connectivity to transmit the audio signal by radio waves from source devices like cellphones and digital players due to the spread of wireless devices in recent years headphones are increasingly used by people in public places such as sidewalks grocery stores and public transit headphones are also used by people in various professional contexts such as audio engineers mixing sound for live concerts or sound recordings and djs who use headphones to cue up the next song without the audience hearing aircraft pilots and call center employees the latter two types of employees use headphones with an integrated microphone history brandes radio headphones circa 1920 headphones originated from the telephone receiver earpiece and were the only way to listen to electrical audio signals before amplifiers were developed the first truly successful set was developed in 1910 by nathaniel baldwin who made them by hand in his kitchen and sold them to the united states navy these early headphones used moving iron drivers with either singleended or balanced armatures the common singleended type used voice coils wound around the poles of a permanent magnet which were positioned close to a flexible steel diaphragm the audio current through the coils varied the magnetic field of the magnet exerting a varying force on the diaphragm causing it to vibrate creating sound waves the requirement for high sensitivity meant that no damping was used so the frequency response of the diaphragm had large peaks due to resonance resulting in poor sound quality these early models lacked padding and were often uncomfortable to wear for long periods their impedance varied headphones used in telegraph and telephone work had an impedance of 75ohms those used with early wireless radio had more turns of finer wire to increase sensitivity impedance of 1000 to 2000ohms was common which suited both crystal sets and triode receivers some very sensitive headphones such as those manufactured by brandes around 1919 were commonly used for early radio work in early powered radios the headphone was part of the vacuum tubes plate circuit and carried dangerous voltages it was normally connected directly to the positive high voltage battery terminal and the other battery terminal was securely grounded the use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset in 1958 john c koss an audiophile and jazz musician from milwaukee produced the first stereo headphones smaller earbud type earpieces which plugged into the users ear canal were first developed for hearing aids they became widely used with transistor radios which commercially appeared in 1954 with the introduction of the regency tr1 the most popular audio device in history the transistor radio changed listening habits allowing people to listen to radio anywhere the earbud uses either a moving iron driver or a piezoelectric crystal to produce sound the 35mm radio and phone connector which is the most commonly used in portable application today has been used at least since the sony efm117j transistor radio which was released in 1964 its popularity was reinforced with its use on the walkman portable tape player in 1979 applications headphones may be used with stationary cd and dvd players home theater personal computers or portable devices eg digital audio playermp3 player mobile phone cordless headphones are not connected to their source by a cable instead they receive a radio or infrared signal encoded using a radio or infrared transmission link such as fm bluetooth or wifi 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 sennheiser hd 555 headphones used in audio production environments 2007 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 eliminate acoustic feedback while monitoring their own voice in studio recordings musicians and singers use headphones to play or sing along to a backing track or band in military applications audio signals of many varieties are monitored using headphones wired headphones are attached to an audio source by a cable the most common connectors are 635mm and 35mm phone connectors the larger 635mm connector is more common on fixed location home or professional equipment the 35mm connector remains the most widely used connector for portable application today adapters are available for converting between 635mm and 35mm devices electrical characteristics electrical characteristics of dynamic loudspeakers may be readily applied to headphones because most headphones are small dynamic loudspeakers impedance headphones are available with low or high impedance typically measured at 1khz lowimpedance headphones are in the range 16 to 32ohms and highimpedance headphones are about 100600ohms as the impedance of a pair of headphones increases more voltage at a given current is required to drive it and the loudness of the headphones for a given voltage decreases in recent years impedance of newer headphones has generally decreased to accommodate lower voltages available on battery powered cmosbased portable electronics this has resulted in headphones that can be more efficiently driven by batterypowered electronics consequently newer amplifiers are based on designs with relatively low output impedance the impedance of headphones is of concern because of the output limitations of amplifiers a modern pair of headphones is driven by an amplifier with lower impedance headphones presenting a larger load amplifiers are not ideal they also have some output impedance that limits the amount of power they can provide to ensure an even frequency response adequate damping factor and undistorted sound an amplifier should have an output impedance less than 18 that of the headphones it is driving and ideally as low as possible if output impedance is large compared to the impedance of the headphones significantly higher distortion is present therefore lower impedance headphones tend to be louder and more efficient but also demand a more capable amplifier higher impedance headphones are more tolerant of amplifier limitations but produce less volume for a given output level historically many headphones had relatively high impedance often over 500ohms so they could operate well with highimpedance tube amplifiers in contrast modern transistor amplifiers can have very low output impedance enabling lowerimpedance headphones unfortunately this means that older audio amplifiers or stereos often produce poorquality output on some modern lowimpedance headphones in this case an external headphone amplifier may be beneficial sensitivity sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound it thus indicates how loud the headphones are for a given electrical drive level it can be measured in decibels of sound pressure level per milliwatt db splmw or decibels of sound pressure level per volt db spl v unfortunately both definitions are widely used often interchangeably as the output voltage but not power of a headphone amplifier is essentially constant for most common headphones dbmw is often more useful if converted into dbv using ohms law d b s p l v d b s p l m w 10 log 10 i m p e d a n c e 1000 displaystyle mathrm dbspl mathrm v mathrm dbspl mathrm mw 10cdot log 10frac mathrm impedance 1000 alternatively online calculators can be used once the sensitivity per volt is known the maximum volume for a pair of headphones can be easily calculated from the maximum amplifier output voltage for example for a headphone with a sensitivity of 100db splv an amplifier with an output of 1 root mean square rms voltage produces a maximum volume of 100db pairing high sensitivity headphones with power amplifiers can produce dangerously high volumes and damage headphones the maximum sound pressure level is a matter of preference with some sources recommending no higher than 110 to 120db in contrast the american occupational safety and health administration recommends an average spl of no more than 85dba to avoid longterm hearing loss while the european union standard en 5033212013 recommends that volumes above 85dba include a warning with an absolute maximum volume defined using 404000hz noise of no more than 100db to avoid accidental hearing damage using this standard headphones with sensitivities of 90 100 and 110db splv should be driven by an amplifier capable of no more than 3162 10 and 03162 rms volts at maximum volume setting respectively to reduce the risk of hearing damage the sensitivity of headphones is usually between about 80 and 125dbmw and usually measured at 1khz types headphone size can affect the balance between fidelity and portability generally headphone form factors can be divided into four separate categories circumaural overear supraaural onear earbud and inear circumaural circumaural headphones have large pads that surround the outer ear circumaural headphones sometimes called full size headphones or overear 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 1lb ergonomic headband and earpad design is required to reduce discomfort resulting from weight these are commonly used by drummers in recording supraaural a pair of supraaural onear headphones supraaural headphones or onear 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 supraaural 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 supraaural headphones can be further differentiated by the type of earcups openback 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 speakerlike sound due to including sounds from the environment closedback or sealed styles have the back of the earcups closed they usually block some of the ambient noise closedback headphones usually can produce stronger low frequencies than openback headphones semiopen headphones have a design that can be considered as a compromise between openback headphones and closedback headphones some believe the term semiopen is purely there for marketing purposes there is no exact definition for the term semiopen headphone where the openback approach has hardly any measure to block sound at the outer side of the diaphragm and the closedback approach really has a closed chamber at the outer side of the diaphragm a semiopen headphone can have a chamber to partially block sound while letting some sound through via openings or vents earfitting headphones earphones media all and earbudsmearphones sit in the outer ear earphones 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 uncomfortable inear headphones inear monitor inear monitors extend into the ear canal providing isolation from outside noise inear headphones also known as inear monitors iems or canalphones are small headphones with similar portability to earbuds that are inserted in the ear canal itself iems are higherquality inear headphones and are used by audio engineers and musicians as well as audiophiles the outer shells of inear headphones are made up of a variety of materials such as plastic aluminum ceramic and other metal alloys because inear headphones engage the ear canal they can be prone to sliding 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 customfitting ear canal plugs are made from silicone rubber elastomer or foam custom inear headphones use castings of the ear canal to create custommolded plugs that provide added comfort and noise isolation mixed fitting pivoting earphones this type combines advantages of earbuds and inear headphones depending on the environment and requirements of the user they provide passive noise reduction for quality mode conversation or active music listening or they give control over the sound environment around user in comfort mode stand by or background voicemusic listening headset headset audio a typical example of a headset used for voice chats a headset is a headphone combined with a microphone headsets provide the equivalent functionality of a telephone handset with handsfree 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 singleearpiece mono or a doubleearpiece 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 users mouth or a voicetube type where the microphone is housed in the earpiece and speech reaches it by means of a hollow tube telephone headsets sony ericsson cordless bluetooth headset telephone headsets connect to a fixedline 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 rj9 connector headsets are also available with 25mm jack sockets for many dect phones and other applications cordless bluetooth headsets are available and often used with mobile telephones headsets are widely used for telephoneintensive 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 pinalignment 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 ambient noise reduction inears are among those good for noise isolation unwanted sound from the environment can be reduced by excluding sound from the ear by passive noise isolation or often in conjunction with isolation by active noise cancellation passive noise isolation is essentially using the body of the earphone either over or in the ear as a passive earplug that simply blocks out sound the headphone types that provide most attenuation are inear canal headphones and closedback headphones both circumaural and supra aural openback and earbud headphones provide some passive noise isolation but much less than the others typical closedback headphones block 8 to 12db and inears anywhere from 10 to 15db some models have been specifically designed for drummers to facilitate the drummer monitoring the recorded sound while reducing sound directly from the drums as much as possible such headphones claim to reduce ambient noise by around 25db active noisecancelling headphones use a microphone amplifier and speaker to pick up amplify and play ambient noise in phasereversed form this to some extent cancels out unwanted noise from the environment without affecting the desired sound source which is not picked up and reversed by the microphone they require a power source usually a battery to drive their circuitry active noise cancelling headphones can attenuate ambient noise by 20db or more but the active circuitry is mainly effective on constant sounds and at lower frequencies rather than sharp sounds and voices some noise cancelling headphones are designed mainly to reduce lowfrequency engine and travel noise in aircraft trains and automobiles and are less effective in environments with other types of noise transducer technology headphones use various types of transducer to convert electrical signals to sound movingcoil a typical movingcoil headphone transducer the moving coil driver more commonly referred to as a dynamic driver is the most common type used in headphones it consists of a stationary magnet element affixed to the frame of the headphone which sets up a static magnetic field the magnet in headphones is typically composed of ferrite or neodymium a voice coil a light coil of wire is suspended in the magnetic field of the magnet attached to a diaphragm typically fabricated from lightweight highstiffnesstomassratio cellulose polymer carbon material paper or the like when the varying current of an audio signal is passed through the coil it creates a varying magnetic field that reacts against the static magnetic field exerting a varying force on the coil causing it and the attached diaphragm to vibrate the vibrating diaphragm pushes on the air to produce sound waves electrostatic electrostatic loudspeaker diagram electrostatic drivers consist of a thin electrically charged diaphragm typically a coated pet film membrane 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 this field the diaphragm is drawn towards one of the plates air is forced through the perforations combined with a continuously changing electrical signal driving the membrane a sound wave is generated electrostatic headphones are usually more expensive than movingcoil ones and are comparatively uncommon in addition a special amplifier is required to amplify the signal to deflect the membrane which often requires electrical potentials in the range of 100 to 1000volts due to the extremely thin and light diaphragm membrane often only a few micrometers thick and the complete absence of moving metalwork the frequency response of electrostatic headphones usually extends well above the audible limit of approximately 20khz the high frequency response means that the low midband distortion level is maintained to the top of the audible frequency band which is generally not the case with moving coil drivers also the frequency response peakiness regularly seen in the high frequency region with moving coil drivers is absent welldesigned electrostatic headphones can produce significantly better sound quality than other types electrostatic headphones require a voltage source generating 100v to over 1kv and are on the users head since the invention of insulators theres no actual danger they do not need to deliver significant electric current which further limits the electrical hazard to the wearer in case of fault electret an electret driver functions along the same electromechanical means as an electrostatic driver however the electret driver has a permanent charge built into it whereas electrostatics have the charge applied to the driver by an external generator electret and electrostatic headphones are relatively uncommon original electrets were also typically cheaper and lower in technical capability and fidelity than electrostatics patent applications from 20092013 have been approved that show by using different materials ie a fluorinated cyclic olefin electret film frequency response chart readings can reach 50khz at 100db when these new improved electrets are combined with a traditional dome headphone driver headphones can be produced that are recognised by the japan audio society as worthy of joining the hi res audio program us patents 8559660 b2 7732547 b27879446 b27498699 b2 orthodynamic orthodynamic also known as planar magnetic headphones use similar technology to electrostatic headphones with some fundamental differences they operate similarly to planar magnetic loudspeakers an orthodynamic driver consists of a relatively large membrane that contains an embedded wire pattern this membrane is suspended between two sets of permanent oppositely aligned magnets a current passed through the wires embedded in the membrane produces a magnetic field that reacts with the field of the permanent magnets to induce movement in the membrane which produces sound balanced armature balanced armature transducer with armature balanced and exerting no force on diaphragm a balanced armature is a sound transducer design primarily intended to increase the electrical efficiency of the element by eliminating the stress on the diaphragm characteristic of many other magnetic transducer systems as shown schematically in the first diagram it consists of a moving magnetic armature that is pivoted so it can move in the field of the permanent magnet when precisely centered in the magnetic field there is no net force on the armature hence the term balanced as illustrated in the second diagram when there is electric current through the coil it magnetizes the armature one way or the other causing it to rotate slightly one way or the other about the pivot thus moving the diaphragm to make sound a custom inear monitor which uses 8 balanced armatures in a triple crossover configuration 4 low2 mid2 high headphone designs often use multiple balanced armatures to provide a higher fidelity sound the design is not mechanically stable a slight imbalance makes the armature stick to one pole of the magnet a fairly stiff restoring force is required to hold the armature in the balance position although this reduces its efficiency this design can still produce more sound from less power than any other popularized in the 1920s as baldwin mica diaphragm radio headphones balanced armature transducers were refined during world war ii for use in military sound powered telephones some of these achieved astonishing electroacoustic conversion efficiencies in the range of 20 to 40 for narrow bandwidth voice signals today they are typically used only in inear headphones and hearing aids where their high efficiency and diminutive size is a major advantage they generally are limited at the extremes of the hearing spectrum eg below 20hz and above 16khz and require a better seal than other types of drivers to deliver their full potential higherend models may employ multiple armature drivers dividing the frequency ranges between them using a passive crossover network a few combine an armature driver with a small movingcoil driver for increased bass output the earliest loudspeakers for radio receivers used balanced armature drivers for their cones thermoacoustic technology the thermoacoustic effect generates sound from the audio frequency joule heating of the conductor an effect that is not magnetic and does not vibrate the speaker in 2013 a carbon nanotube thinyarn earphone based on the thermoacoustic mechanism was demonstrated by a research group in tsinghua university other transducer technologies transducer technologies employed much less commonly for headphones include the heil air motion transformer amt piezoelectric film ribbon planar magnetic magnetostriction and plasmaionisation the first heil amt headphone was marketed by ess laboratories and was essentially an ess amt tweeter from one of the companys speakers being driven at full range since the turn of the century only precide of switzerland have manufactured an amt headphone piezoelectric film headphones were first developed by pioneer their two models used a flat sheet of film that limited the maximum volume of air movement currently taket produces a piezoelectric film headphone shaped similarly to an amt transducer but which like the precide driver has a variation in the size of transducer folds over the diaphragm it additionally incorporates a two way design by its inclusion of a dedicated tweetersupertweeter panel the folded shape of a diaphragm allows a transducer with a larger surface area to fit within smaller space constraints this increases the total volume of air that can be moved on each excursion of the transducer given that radiating area magnetostriction headphones sometimes sold under the label bonephones work by vibrating against the side of head transmitting sound via bone conduction this is particularly helpful in situations where the ears must be unobstructed or for people who are deaf for reasons that dont affect the nervous apparatus of hearing magnetostriction headphones though are limited in their fidelity compared to conventional headphones that rely on the normal workings of the ear additionally in the early 1990s a french company called plasmasonics tried to market a plasmaionisation headphone there are no known functioning examples left benefits and limitations two sony mdrv6 headphones one folded for travel headphones can prevent other people from hearing the sound either for privacy or to prevent disturbing others as in listening in a public library they can also provide a level of sound fidelity greater than loudspeakers of similar cost part of their ability to do so comes from the lack of any need to perform room correction treatments with headphones highquality headphones can have an extremely flat lowfrequency response down to 20hz within 3db while a loudspeaker must use a relatively large often 15 or 18 speaker driver to reproduce low frequencies headphones can accurately reproduce bass and subbass frequencies with speaker drivers only 4050 millimeters wide or much smaller as is the case with inear monitor headphones headphones impressive lowfrequency performance is possible because they are so much closer to the ear that they only need to move relatively small volumes of air marketed claims such as frequency response 4hz to 20khz are usually overstatements the products response at frequencies lower than 20hz is typically very small headphones are also useful for video games that use 3d positional audio processing algorithms as they allow players to better judge the position of an offscreen sound source such as the footsteps of an opponent or their gun fire although modern headphones have been particularly widely sold and used for listening to stereo recordings since the release of the walkman there is subjective debate regarding the nature of their reproduction of stereo sound stereo recordings represent the position of horizontal depth cues stereo separation via volume and phase differences of the sound in question between the two channels when the sounds from two speakers mix they create the phase difference the brain uses to locate direction through most headphones because the right and left channels do not combine in this manner the illusion of the phantom center can be perceived as lost hard panned sounds are also heard only in one ear rather than from one side binaural recordings use a different microphone technique to encode direction directly as phase with very little amplitude difference below 2khz often using a dummy head they can produce a surprisingly lifelike spatial impression through headphones commercial recordings almost always use stereo recording rather than binaural because loudspeaker listening is more common than headphone listening it is possible to change the spatial effects of stereo sound on headphones to better approximate the presentation of speaker reproduction by using frequencydependent crossfeed between the channels headsets can have ergonomic benefits over traditional telephone handsets they allow call center agents to maintain better posture without needing to handhold a handset or tilt their head sideways to cradle it dangers and volume solutions see also automatic volume limiter product testing headphones in an anechoic chamber using headphones at a sufficiently high volume level may cause temporary or permanent hearing impairment or deafness the headphone volume often has to compete with the background noise especially in loud places such as subway stations aircraft and large crowds extended periods of exposure to high sound pressure levels created by headphones at high volume settings may be damaging some manufacturers of portable music devices have attempted to introduce safety circuitry that limited output volume or warned the user when dangerous volume was being used but the concept has been rejected by most of the buying public which favors the personal choice of high volume koss introduced the safelite line of cassette players in 1983 with such a warning light the line was discontinued two years later for lack of interest the government of france has imposed a limit on all music players sold in the country motorcycle and other powersport riders benefit by wearing foam earplugs when legal to do so to avoid excessive road engine and wind noise but their ability to hear music and intercom speech is actually enhanced when doing so the ear can normally detect 1billionth of an atmosphere of sound pressure level the risk of hearing damage also depends on the exposure time the higher the volume the faster hearing loss occurs according to osha work safety guidelines workers should be exposed to 90dba noise for a maximum of 8 hours to avoid hearing loss an increase to just 95dba cuts the safe exposure to only 4 hours but there is little specific consensus on the safe level of exposure niosh has an 8hour recommended exposure limit set to 85dba additionally an increase to 93dba instead of 95dba halves the safe exposure time to 4 hours some studies have found that people are more likely to raise volumes to unsafe levels while performing strenuous exercise recommended that exercisers should set their headphone volumes to half of their normal loudness and only use them for half an hour noise cancelling headphones can be considered dangerous because of a lack of awareness the listener may have with their environment noise cancelling headphones are so effective that a person may not be able to hear oncoming traffic or pay attention to people around them there is also a general danger that music in headphones can distract the listener and lead to dangerous situations the usual way of limiting sound volume on devices driving headphones is by limiting output power this has the additional undesirable effect of being dependent of the efficiency of the headphones a device producing the maximum allowed power may not produce adequate volume when paired with lowefficiency highimpedance equipment while the same amount of power can reach dangerous levels with very efficient earphones bone conduction digital audio player earpad headphone amplifier inear monitor list of headphone manufacturers noisecancelling headphones wikimedia commons has media related to headphones look up headphone earphone earpiece stereophone or canalphones in wiktionary the free dictionary vtemusic technologymusic technology mechanical electrical electronic and digital sound recording audio channel audio console mixing board binaural recording digital audio workstation daw effects unit equalizer headphones microphone microphone preamplifier monitor speaker multitrack recording music production music sequencer outboard gear recording media phonograph record magnetic tape compact cassette compact disc dat hard disk minidisc mp3 opus analog recording 8track cartridge amplifier cassette deck comparison of analog and digital recording experimental musical instrument phonograph player piano reeltoreel audio tape recording tape recorder playback transducers loudspeaker headphones monitor speaker pa system sound reinforcement system speaker enclosure subwoofer digital audio digital recording digital signal processing live music audio console bass amplifier effects unit foldback guitar amplifier keyboard amplifier pa system radio reverberation sound reinforcement system electronic music chiptune circuit bending drum machine electronic drums electronic musical instrument midi midi controller music workstation sampler sequencer sound module synthesizer theremin software digital audio editor digital audio workstation garageband protools scorewriter software effect processor software sampler software synthesizer professions audio engineer dj guitar technician mixing engineer monitor engineer piano tuner record producer rerecording mixer sound designer sound follower sound operator sound recording engineer tape op people and organizations audio engineering society goji electronics institute of broadcast sound lejaren hiller ircam max mathews musical electronics library professional lighting and sound association robert moog smpte steim related topics audiophile high fidelity home audio home cinema music store professional audio store new interfaces for musical expression nime vehicle audio 