A user wears headphones, which are a pair of miniature loudspeaker speakers, on or near their head over their ears. They function as electroacoustic transducers, converting an electrical signal into an associated sound. Using headphones allows a single user to listen to an audio source in privacy, as opposed to using a loudspeaker, which broadcasts sound for everyone nearby to hear. Earphones, ear speakers, and cans are other names for headphones. A band placed over the top of the head secures the speakers in place on circumoral ('around the ear') and supra-aural ('over the ear') headphones.
Earbuds or earpieces are a different kind and are made up of individual components that connect into the user's ear canal. Bone conduction headphones are a third variety; these often encircle the back of the head and rest in front of the ear canal, leaving the ear canal unobstructed. A headset is a headphone and microphone combo used in communications.
Using a cord or wireless technology like Bluetooth, DECT, or FM radio, headphones can be connected to a signal source such an audio amplifier, radio, CD player, portable media player, mobile phone, video game console, or electronic musical instrument. In order to free up their hands so they could operate the telephone, the first headphones were created in the late 19th century. High fidelity headphones represented an improvement above the initial subpar audio quality.
Different audio reproduction quality characteristics are displayed by headphones. Usually, headsets made for telephone use are unable to reproduce sound with the high fidelity of pricey devices made for audiophiles. For connecting to the audio source, headphones with cables often include a 1/4 inch (6.35mm) or 1/8 inch (3.5mm) phone jack. Some stereo earbuds are wireless, transmitting the audio signal via radio waves from source devices such cellphones and digital players via Bluetooth connectivity.
Beginning in the 1980s, headphones started to be worn in public settings like sidewalks, supermarkets, and public transportation as a result of the Walkman effect. People who use headphones professionally include audio engineers who mix sound for live performances or sound recordings, DJs who use them to cue the next song without the audience hearing, pilots of airplanes, and contact center staff. The last two employee categories use headphones with a built-in microphone.
The requirement for hands-free phone use led to the development of headphones. The "hands-free" headphones were preceded by a number of iterative products. By the 1890s, a British business called Electrophone had developed the first indisputably headphone-like gadget. With the help of this equipment, their customers could connect to live feeds of performances at theaters and opera houses all across London. The performance could be heard by subscribers through a set of enormous earphones attached below the chin and held by a long rod.
In 1891, French engineer Ernest Mercadier received U.S. Patent No. 454,138 for "improvements in telephone-receivers...which shall be light enough to be carried while in use on the head of the operator." Mercadier's invention was a set of in-ear headphones.
A prototype telephone headset was created in 1910 by Utahn Nathaniel Baldwin as a result of his inability to hear sermons on Sundays. The US Navy accepted his offer to test it and immediately placed an order with Baldwin for 100. Baldwin Radio Company and Wireless Specialty Apparatus Co. established a production plant in Utah to handle orders. His discoveries served as the foundation for the "sound-powered" or electricity-free telephones that were in use during World War II.
Before amplifiers were created, electrical audio signals could only be heard by headphones, which are a direct descendant of the telephone receiver earpiece.
Moving iron drivers, either single-ended or balanced armatures, were employed in these early headphones. Voice coils were wrapped around a permanent magnet's poles in the common single-ended kind, which was placed close to a flexible steel diaphragm. The magnetic field of the magnet was changed by the audio current flowing through the coils, changing the force acting on the diaphragm, causing it to vibrate and producing sound waves.
Due to the great sensitivity required, no dampening was applied, which caused the diaphragm's frequency response to have big peaks due to resonance and poor sound quality. Early versions lacked padding and were frequently uncomfortable to wear continuously. Their impedance varied; telegraph and telephone headsets had an impedance of 75 ohms, for example. To boost sensitivity, those used with early wireless radio featured more turns of finer wire. Impedance of 1,000 to 2,000 ohms was typical and suited both triode receivers and crystal sets. For early radio work, some extremely sensitive headphones—like those made by Brandes around 1919—were frequently employed.
The headphone in early powered radios was connected to the vacuum tube's hazardous plate circuit and carried electricity. Normally, it was firmly grounded on the other battery terminal and linked directly to the positive high voltage battery terminal. Users ran the risk of getting shocked if they touched the exposed headphone cables when adjusting an uncomfortable headset because bare electrical connections were used.
Milwaukee-born jazz musician and audiophile John C. Koss created the first pair of stereo headphones in 1958.
Hearing aid earpieces were the first devices that use smaller earbud-style earpieces that plugged into the user's ear canal. When the Regency TR-1 was released in 1954, transistor radios—which first appeared on the market—became widely used. The transistor radio, which altered listening patterns by enabling people to listen to radio anywhere, is the most widely used audio device in history. The sound is produced by the earbud using either a piezoelectric crystal or a moving iron driver. Today's most popular radio and phone connector, the 3.5 mm connector, has been around since at least the 1964 debut of the Sony EFM-117J transistor radio. Its inclusion on the Walkman portable tape player in 1979 increased its notoriety.
As long as these devices have a headphone jack, headphones can be used with stationary CD and DVD players, home theater systems, personal computers, or portable devices (such as digital audio players/MP3 players, mobile phones). No cable is used to connect cordless headphones to their source. They instead receive radio or infrared signals that have been encoded using a radio or infrared transmission link, such FM, Bluetooth, or Wi-Fi. These are receiver systems that run on batteries, and the headphones are but one part of the system. When attending events like a silent disco or silent gig, cordless headphones are used.
In the world of professional audio, DJs using a DJ mixer and sound engineers use headphones to monitor signal sources while performing live. When speaking into the microphone in radio studios, DJs wear headphones with the speakers off to prevent acoustic feedback as they listen to their own voice. Musicians and singers use headphones during studio recordings to play or sing along with a band or backing track. Many different audio streams are monitored using headphones in military applications.
A cable connects wired headphones to an audio source. The most used connectors are 3.5 mm phone connectors and 6.35 mm (1/4′′) connectors. On stationary home or business equipment, the bigger 6.35 mm connector is more prevalent. Today, the 3.5 mm connector is still the most frequently used connector for portable devices. For converting between 6.35 mm and 3.5 mm devices, adapters are available.
Due to the need for internal hardware like a battery, a charging controller, a speaker driver, and a wireless transceiver, wireless headphones tend to be more expensive because they are an active component. In contrast, wired headphones are a passive component because speaker driving is delegated to the audio source.
Some headphone wires come with a serial potentiometer that controls the volume.
Some wired headphones have two ports to allow connecting another wired headphone in a parallel circuit, which splits the audio signal to share with another participant but can also be used to hear audio from two inputs simultaneously. Wired headphones can be equipped with a non-detachable cable or a detachable auxiliary male-to-male plug. This function can be retrofitted using an external audio splitter.
Applications for audiometric testing
The condition of the auditory system is also assessed using a variety of specially made headphones or earphones in the field of audiology for determining hearing thresholds, medically diagnosing hearing loss, locating additional diseases related to hearing, and monitoring hearing status in occupational hearing conservation programs. Due to the simplicity of calibration and the ability to compare findings between testing facilities, specific headphones models have been selected as the standard.
Since they are the simplest to calibrate and were once the norm, supra-aural style headphones are traditionally the ones that are used the most in audiology. The Telephonics Dynamic Headphone (TDH) 39, TDH-49, and TDH-50 are popular models. Since they offer greater interaural attenuation, introduce less variability when testing 6,000 and 8,000 Hz, and prevent testing difficulties brought on by compressed ear canals, in-the-ear or insert style earphones are utilized more frequently today. The Etymotic Research ER-3A insert earphone type is a popular choice. In order to determine hearing thresholds in the extended high frequency range, circum-aural earphones are also utilized (8,000 Hz to 20,000 kHz).
The only models with reference equivalent threshold sound pressure level values for the extended high frequency range according to ANSI standards are the Sennheiser HDA300 and Koss HV/1A circumaural earphones.
Headphones and audiometers need to be calibrated simultaneously. In order to verify that the output signal from the audiometer to the headphones is accurate to the reading on the audiometer for sound pressure level and frequency, the signal is monitored with a sound level meter during the calibration process. The earphones are placed in an auditory coupler designed to replicate the transfer function of the outer ear during calibration.
Because particular headphones are required for the initial calibration of the audiometer, any other pair, even from the same brand and model, cannot be used in their stead.
Impedance
There are headphones with high or low impedance available (typically measured at 1 kHz). High-impedance headphones often vary from 100 to 600 ohms, whereas low-impedance headphones fall between 16 and 32 ohms. A set of headphones becomes less loud for a given voltage as its impedance rises, requiring more voltage (at a given current) to drive them. Modern headphones' impedance has generally dropped in recent years to accommodate the lower voltages made possible by battery-powered CMOS-based portable devices. As a result, battery-powered electronics can now operate headphones more effectively. As a result, more recent amplifier designs have an output impedance that is relatively low.
Due to amplifier power restrictions, the impedance of headphones is a concern. A modern set of headphones is powered by an amplifier, and headphones with a lower impedance put out more of a load. The output impedance of amplifiers also restricts the amount of power they can produce, making them less than ideal. An amplifier's output impedance should be less than 1/8 that of the headphones it is driving in order to guarantee a consistent frequency response, proper damping factor, and undistorted audio (and ideally, as low as possible). Significantly more distortion is evident if the output impedance is high in comparison to the impedance of the headphones. Because of this, headphones with a lower impedance are typically louder and more effective, but they also require a stronger amplifier.
Higher impedance headphones provide less volume for a given output level, but they are more forgiving to amplifier restrictions.
For use with high-impedance tube amplifiers, many headphones had relatively high impedance in the past—often exceeding 500 ohms. Modern transistor amplifiers, on the other hand, can have extremely low output impedances, allowing for lower-impedance headphones. Unfortunately, this implies that some contemporary, low-impedance headphones frequently create poor-quality output when used with older audio amplifiers or stereos. An external headphone amplifier might be useful in this situation.
The ability of an earphone to translate an incoming electrical signal into audible sound is known as its sensitivity. Thus, it provides a measurement of the volume of the headphones at a given electrical driving level. Decibels of sound pressure level per volt or decibels of sound pressure level per milliwatt (dB (SPL)/mW) can be used to measure it. [18] Unfortunately, both definitions are frequently and widely employed in the same context. dB/mW is frequently more useful if translated into dB/V using Ohm's law since the output voltage (but not power) of a headphone amplifier is essentially constant for the majority of typical headphones:
Alternatives include using internet calculators. The maximum loudness for a set of headphones can be simply estimated from the maximum amplifier output voltage if the sensitivity per volt is known. For instance, an amplifier with an output of 1 root mean square (RMS) voltage will create a maximum loudness of 100 dB for headphones with a sensitivity of 100 dB (SPL)/V.
High noise levels and damage to headphones can result from using power amplifiers with high sensitivity headphones. Depending on personal preference, the maximum sound pressure level should not exceed 110 to 120 dB. Contrarily, the European Union standard EN 50332-1:2013 advises that volumes above 85 dB(A) include a warning, with an absolute maximum volume (defined using 40-4,000 Hz noise) of no more than 100 dB to prevent accidental hearing damage. The American Occupational Safety and Health Administration recommends an average SPL of no more than 85 dB(A) to prevent long-term hearing loss.
According to this guideline, in order to lessen the danger of hearing damage, headphones with sensitivities of 90, 100, and 110 dB (SPL)/V should be driven by an amplifier with a maximum output of no more than 3.16, 1.0, and 0.3162 RMS volts, respectively.
The sensitivity of headphones is typically evaluated at 1 kHz and ranges between 80 and 125 dB/mW.
The trade-off between fidelity and portability can be influenced by headphone size. The four distinct categories of headphone form factors are circumaural (over-ear), supra-aural (on-ear), earbud, and in-ear.
Connectivity
Wired
headphones with soldered cables for the headphone jack.
Wireless
On-ear wireless headphones. frequently includes a headphone jack.
over-ear headphones that are wireless. frequently includes a headphone jack.
Bluetooth neckband-connected wireless earphones.
True wireless earphones don't have a connection connecting them to one another. They use Bluetooth and other wireless technologies to deliver audio from a hardware device.
Ear adaption
Circumaural
Circular or ellipsoid earpads on circumaural headphones, also known as full size or over-ear headphones, surround the ears. Circumaural headphones can be made to entirely seal against the head to reduce outside noise because they totally enclose the ear. Circumaural headphones can be heavy due to their size; some pairs weigh more than 500 grams (1 lb). It is necessary to have an ergonomic headband and earpad design to lessen pain brought on by weight. Drummers frequently use them when recording.
The pads of on-ear or supra-aural headphones press against the ears rather than around them. In the 1980s, they were frequently included with portable stereos. There is less suppression of outside noise with this type of headphone than with circumaural headphones because they are often smaller and lighter. Compared to circumaural headphones that sit around the ear, supra-aural headphones put pressure on the ear, which can cause pain. The material of the earcups may affect comfort.
Ear-fitting headphones
Earphones
Earphones are extremely tiny headphones that are put into the outer ear and face the ear canal without really going inside. Even though earphones are lightweight and portable, many people find them to be uncomfortable. They offer very little acoustic isolation and allow ambient noise to enter; users may dangerously increase the level to make up for this, which runs the risk of suffering hearing loss. However, they also enable the user to become more aware of their surroundings. Earphones have frequently been included with portable music players since since the invention of the transistor radio. For comfort, they are occasionally sold with foam or rubber padding.
(Earbuds have been around at least since 1984, but the name didn't become widely used until until 2001, when Apple's MP3 player became popular.)
In-ear headphones, commonly referred to as in-ear monitors (IEMs) or canalphones, are small, portable headphones that fit inside the ear canal. Audio engineers, musicians, and audiophiles all utilize IEMs, which are higher-quality in-ear headphones.
In-ear headphones include a range of materials for their exterior shells, including plastic, aluminum, ceramic, and other metal alloys. In-ear headphones block out a lot of outside noise but can be prone to sliding out since they engage the ear canal. When sound is a crucial cue for safety or other reasons, such as when walking, driving, or riding in or near motor traffic, the absence of sound from the surroundings might be problematic. Some in-ear headphones have built-in microphones that, when desired, let you hear some ambient noise.
Silicone rubber, elastomer, or foam are the materials used to create generic or custom-fit ear canal plugs. Lower-end devices may have interchangeable plugs, which raises the possibility of their coming loose and becoming stuck in the ear canal. Custom in-ear headphones produce molded plugs that are more comfortable and noise-isolating using castings of the ear canal.
Some wireless earphones come with a case for charging.
Open- or closed-back
The kind of earcups on circumaural and supraaural headphones might help to further distinguish them:\
The back of the earcups of headphones with an open back are exposed. This results in increased sound leakage from the headphones and more ambient noise entering them, but because it also includes sounds from the environment, the sound is more realistic or speaker-like.
Semi-open
A compromise between closed-back headphones and open-back headphones can be found in semi-open headphones. Some people think the word "semi-open" is only used to promote products. The term "semi-open headphone" is not precisely defined. A semi-open headphone can have a chamber to partially block sound while letting some sound through via openings or vents, in contrast to the open-back approach which has hardly any measure to block sound at the outer side of the diaphragm and the closed-back approach which really has a closed chamber at the outer side of the diaphragm.
Closed-back
The rear of the earcups are closed in closed-back (also known as sealed) designs. Typically, they reduce some of the background noise. When compared to open-back headphones, closed-back headphones typically produce higher low frequencies.
A headset combines a set of headphones with a microphone. With hands-free operation, headsets offer the same functionality as a phone handset. Aviation, theatre or television studio intercom systems, console or PC gaming, and telephone use are just a few uses for headsets. Earpieces in headsets can either be single (mono) or double (dual) (mono to both ears or stereo). Either an external microphone, which is held in front of the user's mouth, or a voicetube, which is placed in the earpiece and receives speech through a hollow tube, make up the microphone arm of headsets.
Telephone headsets
A fixed-line telephone system is connected by telephone headsets. The handset of a phone is replaced by a telephone headset. Standard 4P4C connectors, sometimes known as RJ-9 connectors, are installed in headsets for conventional corded telephones. For many DECT phones and other applications, headsets with 2.5 mm jack sockets are furthermore offered. Bluetooth headphones that are cordless are readily accessible and frequently used with mobile phones. For telephone-intensive tasks, headsets are frequently utilized, especially by call center employees. Anyone who wants to use one hand free to hold a phone conversation also uses them.
Older telephone models have a headset microphone impedance that differs from the original handset, necessitating the use of a headset amplifier. Similar to a telephone headset adaptor, a telephone amplifier aligns the basic pins, but it also provides sound amplification for the microphone and loudspeakers. Most versions of telephone amplifiers feature volume adjustment for speakers as well as microphone, mute function and switching between headset and handset. Telephone amplifiers are powered by batteries or AC adaptors.
Communication headsets are typically made out of a headphone with an attached microphone and are used for two-way communication. These headsets are employed by a wide range of vocations, including those in the military, sports, music, and many service-related industries. Depending on the usage, required noise attenuation, and required communication fidelity, they come in a variety of sizes and shapes.
Ambient noise reduction
By eliminating sound from the ear through passive noise isolation or, frequently in conjunction with isolation, by active noise cancellation, unwanted environmental noise can be eliminated.
In-ear headphones are among the best at blocking out noise.
In essence, passive noise isolation involves employing the earphone's body, which can be worn over or in the ear, as a passive earplug that merely muffles sound. In-ear canal headphones and closed-back headphones, both circumaural and supra aural, offer the greatest attenuation. Although far less than the other types, open-back and earbud headphones do offer some passive noise isolation.
Typical closed-back headphones block 8 to 12 dB, but in-ear headphones can block anywhere between 10 and 15 dB. Some types were created especially for drummers, allowing them to monitor the recorded music while minimizi
ng direct drum sound as much as possible. Such headphones advertise a 25 dB reduction in background noise.
In order to partially cancel out undesired noise from the environment without impacting the intended sound source, active noise-cancelling headphones employ a microphone, amplifier, and speaker to pick up, amplify, and broadcast ambient noise in phase-reversed form. Their electronics needs to be powered, typically by a battery. Active noise canceling headphones can reduce background noise by 20 dB or more, but their active circuitry is more effective at dampening low-frequency, continuous sounds than it is at dampening high-frequency sounds like voices and abrupt sounds. Some noise-canceling headphones are less successful in surroundings with other types of noise because they are primarily made to minimize low-frequency engine and travel noise in vehicles, trains, and airplanes.
In order to partially cancel out undesired noise from the environment without impacting the intended sound source, active noise-cancelling headphones employ a microphone, amplifier, and speaker to pick up, amplify, and broadcast ambient noise in phase-reversed form. Their electronics needs to be powered, typically by a battery. Active noise canceling headphones can reduce background noise by 20 dB or more, but their active circuitry is more effective at dampening low-frequency, continuous sounds than it is at dampening high-frequency sounds like voices and abrupt sounds. Some noise-canceling headphones are less successful in surroundings with other types of noise because they are primarily made to minimize low-frequency engine and travel noise in vehicles, trains, and airplanes.
Headphones use various types of transducer to convert electrical signals to sound.
The most typical driver used in headphones is the moving coil driver, sometimes known as a "dynamic" driver. It is made comprised of a stationary magnet component that is mounted to the headphone's frame and creates a static magnetic field. In headphones, the magnet is commonly made of ferrite or neodymium. A diaphragm, often made of lightweight, high-stiffness-to-mass-ratio cellulose, polymer, carbon material, paper, or a similar substance, is linked to a voice coil, a light coil of wire suspended in the magnetic field of the magnet.
When an audio signal's variable current is sent through the coil, it generates a variable magnetic field that reacts against the static magnetic field and pulls on the coil with a variable force, causing it to vibrate along with the attached diaphragm. Sound waves are created by the vibrating diaphragm pushing against the air.
A thin, electrically charged membrane, usually a coated PET film membrane, is suspended between two perforated metal plates to form electrostatic drivers (electrodes). The electrodes receive the electrical sound signal, which generates an electrical field. Depending on the polarity of this field, the diaphragm is dragged in the direction of one of the plates. A sound wave is produced when air is propelled through the perforations and a membrane is driven by an electrical signal that is constantly changing. Moving-coil headphones are more popular and typically less expensive than electrostatic headphones. The signal must also be amplified in order to cause the membrane to deflect, which frequently necessitates electrical potentials between 100 and 1,000 volts.
Electrostatic headphones are placed on the user's head and require a voltage source that produces 100 V to more than 1 kV. Since insulators were developed, there is no real risk. They don't have to supply a lot of electric current, which reduces the wearer's electrical hazard in the event of a malfunction.
Electret
An electrostatic driver and an electret driver both operate electromechanically. But unlike electrostatics, where the charge is provided to the driver by an external generator, the electret driver has a permanent charge built into it. Electrostatic and electret headphones are not commonly used. In the beginning, electrets were often less accurate and technically capable than electrostatics. With the use of various materials, such as a "Fluorinated cyclic olefin electret film," it has been demonstrated in patent applications from 2009 to 2013 that frequency response chart readings can approach 50 kHz at 100dB.
It is possible to create headphones that are acknowledged by the Japan Audio Society as deserving of entering the Hi Res Audio program when these new, enhanced electrets are coupled with a conventional dome headphone driver. 8,559,660 B2, 7,732,547 B2.7, 879,446 B2.7, and 498,699 B2 are US patents.
Planar magnetic (also known as orthodynamic) headphones use similar technology to electrostatic headphones, with some fundamental differences. They operate similarly to planar magnetic loudspeakers.
A planar magnetic 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.
A balanced armature is a sound transducer design that, by removing the stress on the diaphragm typical of many other magnetic transducer systems, aims to maximize the electrical efficiency of the element. It comprises of a rotating magnetic armature that can move inside the field of the permanent magnet, as shown schematically in the first diagram. The phrase "balanced" refers to a magnetic field that is properly centered such that there is no net force acting on the armature. According to the second diagram, an electric current flowing through the coil magnetizes the armature in one direction or the other, causing it to rotate slightly about the pivot and moving the diaphragm to produce sound.
Because of a minor imbalance, the armature sticks to one pole of the magnet, making the design mechanically unstable. To keep the armature in the "balancing" position, a rather strong restoring force is needed. Even though this lowers its efficiency, this design still outperforms all others in terms of sound output per unit of power. More information required] Balanced armature transducers, which were first used in the 1920s as Baldwin Mica Diaphragm radio headphones, were improved during World War II for use in military sound driven telephones. For narrow bandwidth voice transmissions, several of these obtained astounding electro-acoustic conversion efficiency, ranging from 20 to 40 percent.
They are only commonly employed in hearing aids and in-ear headphones today, where their great efficiency and small size are significant advantages. They typically have limitations at the upper and lower ends of the audible range (e.g., below 20 Hz and above 16 kHz), and they need a superior seal than other drivers to perform to their maximum capacity. A passive crossover network is used in higher-end models to divide the frequency ranges between numerous armature drivers. For greater bass production, some speakers pair an armature driver with a tiny moving-coil driver.
The cones of the early loudspeakers for radio receivers were powered by balanced armature drivers.
The thermoacoustic effect, which is not magnetic and does not vibrate the speaker, produces sound from the audio frequency Joule heating of the conductor. A research team at Tsinghua University created a carbon nanotube thin-yarn earphone based on the thermoacoustic process in 2013. The CNT thin yarn thermoacoustic chip is the functional component of the CNT thin yarn earphone as it has been manufactured. This type of chip is formed of a layer of CNT thin yarn array supported by a silicon wafer, and periodic grooves with a specific depth are created on the wafer using microfabrication techniques to reduce heat transfer from the CNT yarn to the substrate. Reference needed
Other transducer technologies
The Heil Air Motion Transformer (AMT), Piezoelectric film, Ribbon planar magnetic, Magnetostriction, and Plasma-ionization are a few less frequent transducer technologies used in headphones. The first Heil AMT headset was sold by ESS Laboratories and was effectively a full-range-driven ESS AMT tweeter from a speaker made by the business. Only Precide of Switzerland has produced an AMT headphone since the turn of the century. Pioneer created the first piezoelectric film headphones; each of their two types employed a flat piece of film that constrained the amount of air that could travel. Currently, TakeT makes a piezoelectric film headphone with folds over the diaphragm that are different sizes, comparable to the Precide driver but with an AMT transducer-like form.
Magnetostriction headphones, often known as Bonephones, transmit sound by bone conduction by vibrating against the side of the skull. This is especially beneficial for persons whose ears must be unblocked or for those whose deafness is caused by conditions unrelated to the hearing nerve system. However, compared to traditional headphones that rely on the natural functioning of the ear, magnetostriction headphones have lower levels of fidelity. Additionally, a French business by the name of Plasmasonics attempted to sell a plasma-ionization headphone in the early 1990s. There are no longer any known working examples.
Benefits and limitations
When listening in a public library, for example, headphones might block out other listeners' hearing in order to protect your privacy or avoid upsetting other people. Additionally, they can deliver a level of sound fidelity that is higher than loudspeakers of comparable price. They are able to do this in part because they are not required to use headphones for room correction procedures. An exceptionally flat low-frequency response down to 20 Hz within 3 dB is possible with high-quality headphones.
Low-frequency reproduction requires a speaker driver that is relatively large (typically 15" or 18"), however headphones can reproduce bass and sub-bass frequencies using speaker drivers that are only 40-50 millimeters wide (or much smaller, as is the case with in-ear monitor headphones). Because they are so much closer to the ear, headphones have an amazing low-frequency performance because they only need to move little amounts of air.
It's common for marketing claims like "frequency response 4 Hz to 20 kHz" to be exaggerated; the product's reaction at frequencies lower than 20 Hz is frequently relatively weak. Additionally, headphones are helpful for video games that employ 3D positional audio processing techniques because they enable users to more accurately determine the location of an off-screen sound source (such as the footsteps of an opponent or their gunfire).
Since the introduction of the Walkman, contemporary headphones have been sold and used extensively for stereo music listening, however there is subjective disagreement about how well they reproduce stereo sound. Stereo recordings use the volume and phase differences of the sound in question between the two channels to reflect the position of horizontal depth cues (stereo separation). The phase difference that the brain utilizes to determine direction is produced when the sounds from two speakers are combined. The illusion of the phantom center can be seen as missing while using most headphones because the right and left channels do not mix in this way. Additionally, hard panned sounds are only audible from one side rather than from one ear.
With very little amplitude variation below 2 kHz, binaural recordings need a different microphone approach and frequently employ a dummy head to directly encode direction as phase. Through headphones, they can create a startlingly realistic spatial experience. Due to the more prevalent use of loudspeaker listening over headphone listening in commercial recordings, stereo recording is nearly usually used rather than binaural recording.
By applying frequency-dependent cross-feed between the channels, stereo audio on headphones can be altered to more closely resemble speaker reproduction in terms of spatial effects.
When compared to conventional phone handsets, headsets can provide ergonomic advantages. They eliminate the need for call center employees to hold a phone in their hands or slant their heads to the side to cradle it, allowing them to stand more upright.
Dangers and risks
When headphones are used loudly enough, it may result in acute or long-term hearing loss or deafness. The background noise has to battle with the headphone volume quite a bit, especially in noisy environments like subway stations, airplanes, and crowded areas. Nearly 50% of teenagers and young people (12 to 35 years old) in middle- and high-income nations listen to dangerous levels of sound on their personal audio devices and cellphones. This includes prolonged exposure to high sound pressure levels produced by headphones at high volume settings.
However, a hearing specialist discovered in 2012 (before to smartphones becoming the primary personal listening devices used worldwide) that "less than 5% of users select loud settings and listen regularly enough to cause hearing damage." In its recently released "Guidelines for Safe Listening Devices/Systems," the International Telecommunication Union suggested that sound exposure not exceed 80 dB(A) of A-weighted dB(A) for a maximum of 40 hours per week.
Similar guidelines have been established by the European Union for users of personal listening devices (80 dB(A) for no more than 40 hours per week), with the duration being reduced in half for each additional 3-dB increase in sound exposure (83 dB(A) for no more than 20 hours, 86 dB(A) for 10 hours per week, 89 dB(A) for 5 hours per week, and so on).
Nowadays, the majority of major smartphone manufacturers equip their products with safety or volume-limiting features as well as warning messages. Even said, some buyer segments that want the freedom to choose their own volume levels have had a mixed reaction to such tactics.
On devices driving headphones, sound loudness is typically restricted by limiting output power. A device producing the maximum permitted power may not produce enough volume when paired with low-efficiency, high-impedance equipment, but the same amount of power can reach dangerous levels with very efficient earphones. This has the additional undesirable effect of being dependent on the efficiency of the headphones.
According to certain studies, persons are more prone to elevate their volume to risky levels while engaging in intense activity. According to a Finnish study, users should only wear their headphones for 30 minutes at a time, and at half their usual volume.
A typical risk of loud music listening while wearing headphones is that it can distract the listener, which increases the chance of damage and accidents aside from hearing risk. Noise-cancelling headphones raise the danger level. The wearing of headphones while operating a vehicle or bicycle has been outlawed in a number of nations and jurisdictions.
Also widely reported are cases of contact dermatitis brought on by wearing in-ear headphones like Apple AirPods. In-ear headphones that contain gold, rubber, dyes, acrylates, or methacrylates would result in contact dermatitis. In-ear headphone use and contact dermatitis cases have been linked, although no research have been done to verify that using in-ear headphones will directly result in the condition.
Occupational health and safety
Workers who must wear electronic or communication headsets as part of their regular duties (such as pilots, call center and dispatch operators, sound engineers, firefighters, etc.) are also at risk for hearing impairment from using headphones, and the severity of the damage depends on the exposure period. The National Institute for Occupational Safety and Health (NIOSH) advises that the time-weighted average of sound exposure during an 8-hour workday not exceed 85 dB(A). According to NIOSH, if the sound exposure level rises by three decibels, the exposure period should be halved. This is known as the "time-intensity tradeoff." In order to protect the hearing of workers who must use communication headsets, such as contact center agents, firefighters, musicians, and sound engineers, NIOSH issued a number of papers.
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