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88-471: The Haeco-CSG or Holzer Audio Engineering-Compatible Stereo Generator system was an electronic analog audio signal processing device developed by Howard Holzer, Chief Engineer at A&M Records in Hollywood, California . His company, Holzer Audio Engineering, developed the system in the 1960s during the years of transition from mono to stereophonic sound in popular music recording. The process

176-709: A 1 ⁄ 4 inch (6.4 mm) or 1 ⁄ 8 inch (3.2 mm) phone jack for plugging the headphones into the audio source. Some headphones are wireless, using Bluetooth connectivity to receive the audio signal by radio waves from source devices like cellphones and digital players. As a result of the Walkman effect , beginning in the 1980s, headphones started to be used 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

264-500: 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

352-606: 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. An external audio splitter can retrofit this ability. Various types of specially designed headphones or earphones are also used to evaluate the status of the auditory system in the field of audiology for establishing hearing thresholds, medically diagnosing hearing loss , identifying other hearing related disease, and monitoring hearing status in occupational hearing conservation programs . Specific models of headphones have been adopted as

440-488: 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, high-stiffness-to-mass-ratio cellulose, polymer, carbon material, paper or

528-401: A 120 degree offset. This setting was most commonly used because of its robustness against polarity reversal of audio interconnects down the chain, which can affect the resulting audio when downmixed to mono. Information that is not common to both channels is entirely unaffected as there is no offset phase wave to cancel with. The genius of Holzer's design is in how it overcame the limitations of

616-423: A cable. Instead, they receive a radio or infrared signal encoded using a radio or infrared transmission link, such as FM , Bluetooth or Wi-Fi . These are battery-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

704-469: A cable. The most common connectors are 6.35 mm ( 1 ⁄ 4   inch) and 3.5 mm phone connectors . The larger 6.35 mm connector is more common on fixed location home or professional equipment. The 3.5 mm connector remains the most widely used connector for portable application today. Adapters are available for converting between 6.35 mm and 3.5 mm devices. As active component, wireless headphones tend to be costlier due to

792-558: A digital approach as the techniques of digital signal processing are much more powerful and efficient than analog domain signal processing. Processing methods and application areas include storage , data compression , music information retrieval , speech processing , localization , acoustic detection , transmission , noise cancellation , acoustic fingerprinting , sound recognition , synthesis , and enhancement (e.g. equalization , filtering , level compression , echo and reverb removal or addition, etc.). Audio signal processing

880-512: A given output level. Historically, many headphones had relatively high impedance, often over 500 ohms so they could operate well with high-impedance tube amplifiers . In contrast, modern transistor amplifiers can have very low output impedance, enabling lower-impedance headphones. Unfortunately, this means that older audio amplifiers or stereos often produce poor-quality output on some modern, low-impedance headphones. In this case, an external headphone amplifier may be beneficial. Sensitivity

968-491: A headphone and attached microphone. Such headsets are used in a variety of professions as aviation, military, sports, music, and many service-oriented sectors. They come in all shapes and sizes, depending on use, required noise attenuation, and fidelity of communication needed. 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

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1056-532: A maximum volume of 100 dB. 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 120 dB. In contrast, the American Occupational Safety and Health Administration recommends an average SPL of no more than 85 dB(A) to avoid long-term hearing loss, while

1144-441: A pair of small loudspeaker drivers worn on or around the head over a user's 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 earphones or, colloquially , cans . Circumaural (around

1232-608: A partial cancellation, which is the effect Haeco-CSG takes advantage of. The system electrically rotated the waveform of the right channel by up to 120 degrees to control the buildup of center information during a simple mono downmix. It is not fully known how exactly the circuit accomplished this, however a technician who worked there in 1972–1973, indicates here that the CSG appeared to have split one stereo channel into up to 8 single octave channels followed by eight ganged selectable phase shift networks, controlled via front panel setting. Then

1320-426: A set of in-ear headphones. The German company Siemens Brothers at this time was also selling headpieces for telephone operators which had two earpieces, although placed outside the ear. The Siemens Brothers headpieces looked similar to modern headphones. The majority of headgear used by telephone operators continued to have only one earpiece. Headphones appeared in the emerging field of wireless telegraphy , which

1408-542: A single mix, record companies could manufacture and distribute one version, and vendors could stock one product. Haeco-CSG technology works on the basis of phase cancellation . When two waves that are not in phase are mixed, the resulting waveform has an attenuation in accordance to the degree of shift. For example, two waves which are 180 degrees out of phase will entirely cancel out when mixed together whereas two waves which are entirely in phase will double in amplitude. A difference in phase between 180 and 0 degrees results in

1496-411: A single phase shift network to shift the entire audio bandwidth. A phase shift network is composed of a resistive and a reactive circuit element, either a capacitor or an inductor. Relative values of the two will cause a phase shift (i.e. 90 degrees) at some given frequency that is easily calculated. But the amount of phase shift varies with the frequencies above or below that pass through it, relative to

1584-454: A summing amplifier was used for recombination of multiple audio channels into one, followed by a transformer isolated balanced output. The other channel was not encoded and simply passed thru, via another audio transformer. This is how the effect could be encoded without slightly delaying one channel, which would have only provided close enough to 90 degree phase shift within less than an octave and somewhere between 0 and 180 degrees of phase shift

1672-416: 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 milli watt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V). Unfortunately, both definitions are widely used, often interchangeably. As

1760-505: Is a prime example. As a waveform decays in a large room, it naturally changes phase. In Auto Center phase, this is (generally) shown as the upper frequencies making a drastic change. Tape head misalignment ( azimuth ) also will cause a phase change in upper frequencies. One should be aware of this when attempting to remove Haeco processing and not use auto-phase options. Azimuth alignment adjustment tools can however be used AFTER Haeco has been removed. The "Stereo Tool" plug-in used with Winamp

1848-586: Is able to remove the effect using the Graphic Panner tool (the Automatic Phase Correction tool is unable to accurately do this) by manually selecting the "Phase −90 degrees" preset. The "Auto Center Phase" and "Learn Phase" features will also work, but are not recommended. There are sometimes slight offsets caused by various mixing effects and, to a lesser extent, tape-head misalignment; studio reverb or naturally decaying reverb

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1936-524: Is able to reverse Haeco-CSG. Enable the "Stereo Image Processing" option and adjust the "Angle" setting right to 90 degrees. By adjusting the Winamp plug-in settings under the "Preferences" tab to "out_disk" it is possible to capture the reprocessed audio to a new file. Orban Optimod-PCn (x86 Native) Professional Broadcast Audio Processing Software can be used to effectively remove all HAECO-CSG as well as any other phase/azimuth errors, all automatically. There

2024-625: Is also used to generate human speech using speech synthesis . Audio effects alter the sound of a musical instrument or other audio source. Common effects include distortion , often used with electric guitar in electric blues and rock music ; dynamic effects such as volume pedals and compressors , which affect loudness; filters such as wah-wah pedals and graphic equalizers , which modify frequency ranges; modulation effects, such as chorus , flangers and phasers ; pitch effects such as pitch shifters ; and time effects, such as reverb and delay , which create echoing sounds and emulate

2112-529: Is approached at the highest and lowest frequencies in the audio spectrum. A later version, the CSG-2 in R&;D in 1973 may have encoded both audio channels, but may have used half the phase shift per channel, and perhaps provided a smoother frequency response. The most common listing of 90 degrees out of phase corresponds to Haeco's own recommended setting of the +3 dB build up, whereas no build-up would require

2200-505: Is difficult to predict exactly how the reduction from two channels to one will affect the sound of a particular instrument. Therefore mono sound from a true mono mix is preferable to the use of the Haeco-CSG stereo to mono process. Atlantic Records took out a full page advertisement in the 6 April 1968 issue of Billboard magazine to promote its adoption of the technique, calling it "CSG Stereo". Many A&M Records LP releases during

2288-534: 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 in-ear canal headphones and closed-back headphones, both circumaural and supra aural. Open-back and earbud headphones provide some passive noise isolation, but much less than the others. Typical closed-back headphones block 8 to 12 dB, and in-ears anywhere from 10 to 15 dB. Some models have been specifically designed for drummers to facilitate

2376-488: Is no need for any time or angle settings. The result is always perfect stereo that is perfect mono downmix capable. A description and examples are available at the StreamIndex website. One can also use a simple channel mixer found in most workstations to do a simple correction. By having each channel contain 75% of itself and 25% of the other channel, the "blended" result will be mostly in phase. This, however, will cause

2464-443: 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 1/8 that of

2552-403: Is often still desirable as it often produces nonlinear responses that are difficult to replicate with digital filters. A digital representation expresses the audio waveform as a sequence of symbols, usually binary numbers . This permits signal processing using digital circuits such as digital signal processors , microprocessors and general-purpose computers. Most modern audio systems use

2640-488: Is required to reduce discomfort resulting from weight. These are commonly used by drummers in recording. Supra-aural headphones or on-ear 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

2728-661: Is the Etymotic Research ER-3A. Circum-aural earphones are also used to establish hearing thresholds in the extended high frequency range (8,000 Hz to 20,000 kHz). Along with Etymotic Research ER-2A insert earphones, the Sennheiser HDA300 and Koss HV/1A circum-aural earphones are the only models that have reference equivalent threshold sound pressure level values for the extended high frequency range as described by ANSI standards. Audiometers and headphones must be calibrated together. During

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2816-416: Is the compatibility issue between stereophonic and monaural recordings: information which is identical on both the left and right channels of a stereophonic mix was feared to be too loud when played back on mono AM and FM radio stations and phonographs . When the left and right channels are summed together, any musical parts that are common to both channels combine to be 6 decibels louder than they are in

2904-703: Is the general field of study of algorithms and systems for audio interpretation by machines. Since the notion of what it means for a machine to "hear" is very broad and somewhat vague, computer audition attempts to bring together several disciplines that originally dealt with specific problems or had a concrete application in mind. The engineer Paris Smaragdis , interviewed in Technology Review , talks about these systems — "software that uses sound to locate people moving through rooms, monitor machinery for impending breakdowns, or activate traffic cameras to record accidents." Headphone Headphones are

2992-414: Is used when broadcasting audio signals in order to enhance their fidelity or optimize for bandwidth or latency. In this domain, the most important audio processing takes place just before the transmitter. The audio processor here must prevent or minimize overmodulation , compensate for non-linear transmitters (a potential issue with medium wave and shortwave broadcasting), and adjust overall loudness to

3080-476: Is worn. Circumaural headphones (sometimes called full size headphones or over-ear 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

3168-533: The European Union standard EN 50332-1:2013 recommends 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 avoid accidental hearing damage. Using this standard, headphones with sensitivities of 90, 100 and 110 dB (SPL)/V should be driven by an amplifier capable of no more than 3.162, 1.0 and 0.3162 RMS volts at maximum volume setting, respectively to reduce

3256-498: The University of Surrey in 1987. LPC is the basis for perceptual coding and is widely used in speech coding , while MDCT coding is widely used in modern audio coding formats such as MP3 and Advanced Audio Coding (AAC). An analog audio signal is a continuous signal represented by an electrical voltage or current that is analogous to the sound waves in the air. Analog signal processing then involves physically altering

3344-520: The Sony EFM-117J transistor radio, which was released in 1964. Its popularity was reinforced by its use on the Walkman portable tape player in 1979. Headphones may be used with stationary CD and DVD players , home theater , personal computers , or portable devices (e.g., digital audio player / MP3 player , mobile phone ), as long as these devices are equipped with a headphone jack. Cordless headphones are not connected to their source by

3432-479: The Warner distributed label Sire Records issued a promotional single of " Pop Muzik " by M which contains both short and long versions in CSG processed stereo. This may be the latest known recording to utilize the CSG stereo process. Haeco-CSG can be applied during the mastering stage, near the end of the record production chain. In such cases, the earliest stereo master tapes exist without processing. Therefore,

3520-522: The Warner/Reprise/Atlantic label group from this era had "CSG Mono Process" or "CSG Process" printed on the labels. Artists included Frank Sinatra , Gordon Lightfoot , James Taylor , Seals and Crofts . Warner subsidiary labels such as Atlantic issued a series of mono radio station promotional LPs by progressive rock artists circa 1968–1971. The series included titles by Led Zeppelin , Yes , King Crimson and many others. In 1979,

3608-546: The beginning of the 20th century with inventions like the telephone , phonograph , and radio that allowed for the transmission and storage of audio signals. Audio processing was necessary for early radio broadcasting , as there were many problems with studio-to-transmitter links . The theory of signal processing and its application to audio was largely developed at Bell Labs in the mid 20th century. Claude Shannon and Harry Nyquist 's early work on communication theory , sampling theory and pulse-code modulation (PCM) laid

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3696-543: The biggest selling albums using the process is The Association's Greatest Hits , released in 1968. This recording has sold more than 2 million copies in the United States. The process was also used on the 1968 Frank Sinatra album Cycles as well as on most of the studio recordings on Wheels of Fire by Cream . Early 1968 copies of Neil Young 's self-titled debut album also used the system. The original intention of using Haeco-CSG on commercial LP releases

3784-404: The calibration process, the output signal from the audiometer to the headphones is measured with a sound level meter to ensure that the signal is accurate to the reading on the audiometer for sound pressure level and frequency . Calibration is done with the earphones in an acoustic coupler that is intended to mimic the transfer function of the outer ear. Because specific headphones are used in

3872-416: The characteristics of the original unprocessed sound. The system "blurs" the focus of lead vocals or other sounds mixed to the center of a stereo recording. This is the main reason why Haeco-CSG was usually applied to recordings with bass positioned in one channel only. Bass frequencies are usually centered on modern recordings. The effect today would cause a significant loss of low frequency information, making

3960-416: The continuous signal by changing the voltage or current or charge via electrical circuits . Historically, before the advent of widespread digital technology , analog was the only method by which to manipulate a signal. Since that time, as computers and software have become more capable and affordable, digital signal processing has become the method of choice. However, in music applications, analog technology

4048-461: The desired level. Active noise control is a technique designed to reduce unwanted sound. By creating a signal that is identical to the unwanted noise but with the opposite polarity, the two signals cancel out due to destructive interference . Audio synthesis is the electronic generation of audio signals. A musical instrument that accomplishes this is called a synthesizer. Synthesizers can either imitate sounds or generate new ones. Audio synthesis

4136-716: 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 20 dB 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 low-frequency engine and travel noise in aircraft, trains, and automobiles, and are less effective in environments with other types of noise. Headphones use various types of transducer to convert electrical signals to sound. The moving coil driver , more commonly referred to as

4224-409: 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 25 dB. Active noise-cancelling headphones use a microphone, amplifier, and speaker to pick up, amplify, and play ambient noise in phase-reversed form; this to some extent cancels out unwanted noise from the environment without affecting

4312-550: 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. Some in-ear headphones utilize built-in microphones to allow some outside sound to be heard when desired. Generic or custom-fitting ear canal plugs are made from silicone rubber, elastomer , or foam. Such plugs in lower-end devices may be interchangeable, which increases

4400-409: The ear) and supra-aural (over the ear) headphones use a band over the top of the head to hold the drivers in place. Another type, known as earbuds or earpieces , consists of individual units that plug into the user's ear canal ; within that category have been developed cordless air buds using wireless technology. A third type are bone conduction headphones, which typically wrap around the back of

4488-403: 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

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4576-831: The foundations for the field. In 1957, Max Mathews became the first person to synthesize audio from a computer , giving birth to computer music . Major developments in digital audio coding and audio data compression include differential pulse-code modulation (DPCM) by C. Chapin Cutler at Bell Labs in 1950, linear predictive coding (LPC) by Fumitada Itakura ( Nagoya University ) and Shuzo Saito ( Nippon Telegraph and Telephone ) in 1966, adaptive DPCM (ADPCM) by P. Cummiskey, Nikil S. Jayant and James L. Flanagan at Bell Labs in 1973, discrete cosine transform (DCT) coding by Nasir Ahmed , T. Natarajan and K. R. Rao in 1974, and modified discrete cosine transform (MDCT) coding by J. P. Princen, A. W. Johnson and A. B. Bradley at

4664-507: The head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication , a headset is a combination of a headphone and microphone . Headphones connect to a signal source such as an audio amplifier , radio , CD player , portable media player , mobile phone , video game console , or electronic musical instrument , either directly using a cord, or using wireless technology such as Bluetooth , DECT or FM radio . The first headphones were developed in

4752-400: 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

4840-623: 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 . Communication headsets are used for two-way communication and typically consist of

4928-410: The initial audiometer calibration process, they cannot be replaced with any other set of headphones, even from the same make and model. Electrical characteristics of dynamic loudspeakers may be readily applied to headphones, because most headphones are small dynamic loudspeakers. Headphones are available with high or low impedance (typically measured at 1 kHz). Low-impedance headphones are in

5016-486: The intended phase shift. So a fairly consistent phase delay over the entire audio bandwidth was achieved by using multiple phase delay networks with audio bands restricted to the allowable deviation in desired phase shift versus permissible flatness of the audio response. Generally speaking, Haeco-CSG has a degrading effect on the performance of both stereo and mono sounds processed through the system. The effect can vary substantially from one recording to another depending on

5104-466: The introduction of the Regency TR-1 . The most popular audio device in history, the transistor radio changed listening habits, allowing people to listen to the radio anywhere. The earbud uses either a moving iron driver or a piezoelectric crystal to produce sound. The 3.5 mm radio and phone connector , which is the most commonly used in portable applications today, has been used at least since

5192-487: The late 19th century for use by switchboard operators , to keep their hands free. Initially, the audio quality was mediocre and a step forward was the invention of high fidelity headphones. Headphones exhibit 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

5280-824: 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. 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 with mobile 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,

5368-502: The necessity for internal hardware such as a battery, a charging controller, a speaker driver , and a wireless transceiver , whereas wired headphones are a passive component, outsourcing speaker driving to the audio source. Some headphone cords are equipped with a serial potentiometer for volume control. Wired headphones may be equipped with a non-detachable cable or a detachable auxiliary male-to-male plug, as well as some with two ports to allow connecting another wired headphone in

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5456-433: 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. Headphones grew out of the need to free up a person's hands when operating a telephone . By the 1880s, soon after the invention of the telephone , telephone switchboard operators began to use head apparatuses to mount the telephone receiver . The receiver

5544-566: The other earphone. On other models each earphone receives its audio stream directly from the source device. The former arrangement has the advantage of being compatible with legacy systems while the latter arrangement has the advantage of causing less power drain in the earphone that has to forward one audio stream. Connection between the two earphones also being wireless may be referred to as true wireless stereo (TWS) , offering longer battery life and complete transmission on left and right channels, avoiding possible source signal omission if only one

5632-483: The output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's law : 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 100 dB (SPL)/V, an amplifier with an output of 1 root mean square (RMS) voltage produces

5720-458: The period including popular titles by Sérgio Mendes and Herb Alpert were released with this audio process starting in September 1968. Other record labels soon followed suit, and an estimated 10% of all stereophonic albums released during the late 1960s and early 1970s employed the system. Other labels known to have used the system include Warner Bros. Records and Reprise Records . One of

5808-768: 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 75  ohms . Those used with early wireless radio had more turns of finer wire to increase sensitivity. Impedances of 1,000 to 2,000 ohms

5896-448: The pressure on the ear as compared to circumaural headphones that sit around the ear. Comfort may vary due to the earcup material. 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. They provide hardly any acoustic isolation and leave room for ambient noise to seep in; users may turn up

5984-534: The process can be avoided entirely when such recordings are remastered for compact disc . Remastering without the effect requires a well informed audio engineer who makes an effort to locate the correct master tapes. However the Haeco-CSG processing was often applied at the master tape mix session. This, in effect, makes it a permanent part of the stereo recording. But, the process can still be reversed through modern digital reprocessing. Unfortunately, many compact discs of these processed albums still are encoded with

6072-649: The range 16 to 32 ohms and high-impedance headphones are about 100-600 ohms. 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 CMOS -based portable electronics. This has resulted in headphones that can be more efficiently driven by battery-powered electronics. Consequently, newer amplifiers are based on designs with relatively low output impedance. The impedance of headphones

6160-426: The resulting sound somewhat "tinny". Negative effects of the system can be heard on any stereo speaker system, but makes headphone listening particularly un-natural sounding. This is because the lead vocalist or performer's audio waveform would be attempting to partially cancel itself inside the listener's head, confusing the brain's audio positioning sense. Due to complicated interaction of phase and frequency it

6248-428: The risk of hearing damage. The sensitivity of headphones is usually between about 80 and 125 dB/mW and usually measured at 1 kHz. Headphone size can affect the balance between fidelity and portability. Generally, headphone form factors can be divided into four separate categories: circumaural (over-ear) , supra-aural (on-ear) , earbud and in-ear . Wired headphones make a direct electrical connection to

6336-424: The risk of them falling off and getting lodged in the ear canal. Custom in-ear headphones use castings of the ear canal to create custom-molded plugs that provide added comfort and noise isolation. Some wireless earphones include a charging case. Both circumaural and supra-aural headphones can be further differentiated by the type of earcups: A headset is a headphone combined with a microphone . Headsets provide

6424-542: The same mix when played in stereo (a phenomenon known as "center-channel buildup"). Vocals, solo instruments and bass lines are often mixed equally to both stereo channels — these sounds were contended to be too loud when heard in mono. Because of this fear, separate mono and stereo mixes of the same record were authored, manufactured, and distributed during the 1960s and early 1970s. The Haeco-CSG system appeared to be an attractive option for record companies and retailers by allowing them to cut costs. Engineers could produce

6512-511: The singular form head telephones . By 1908 the headpiece began to be written simply as head phones , and a year later the compound word headphones began to be used. One of the earliest companies to make headphones for wireless operators was the Holtzer-Cabot Company in 1909. They were also makers of head receivers for telephone operators and normal telephone receivers for the home. Another early manufacturer of headphones

6600-456: The sound of different spaces. Musicians, audio engineers and record producers use effects units during live performances or in the studio, typically with electric guitar, bass guitar, electronic keyboard or electric piano . While effects are most frequently used with electric or electronic instruments, they can be used with any audio source, such as acoustic instruments, drums, and vocals. Computer audition (CA) or machine listening

6688-478: The source device using a cable, typically connected with a headphone jack . Modern wireless or cordless earphones have no cord connecting the two earphones to the source device or to each other; they receive audio by means of a wireless technology such as Bluetooth . In historical usage, 'wireless' referred to a connection to a radio receiver, which was known as a wireless. On some models both audio streams are transmitted to one earphone which forwards one stream to

6776-737: The standard due to the ease of calibration and ability to compare results between testing facilities. Supra-aural style headphones are historically the most commonly used in audiology as they are the easiest to calibrate and were considered the standard for many years. Commonly used models are the Telephonics Dynamic Headphone (TDH) 39, TDH-49, and TDH-50. In-the-ear or insert style earphones are used more commonly today as they provide higher levels of interaural attenuation, introduce less variability when testing 6,000 and 8,000 Hz, and avoid testing issues resulting from collapsed ear canals. A commonly used model of insert earphone

6864-547: The stereo separation to be somewhat diminished. While the system is no longer in use anywhere today, the basic idea of shifting the phase to create a mono downmix can be applied today if one has a reason to do so. The "encoding" process is similar to the "decoding" process in the application of a 90 or 120 degree phase shift followed by averaging the channels together in a channel mixer. "Expanded discussion on C.S.G. at Steve Hoffman Forums" . Audio signal processing The motivation for audio signal processing began at

6952-505: The success of Apple's MP3 player. ) In-ear headphones, also known as in-ear monitors (IEMs) or canalphones , are small headphones with similar portability to earbuds that 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. The outer shells of in-ear headphones are made up of a variety of materials, such as plastic, aluminum , ceramic and other metal alloys. Because in-ear headphones engage

7040-465: The system, causing negative effects even on modern digital playback systems. ‹The template Manual is being considered for merging .›   Haeco-CSG processing can be reversed through digital audio workstation software by digitally re-rotating phase of the right channel back by the correct number of degrees. The phase module of iZotope RX allows a user to fully adjust the phase of each stereo audio channel independently. Adobe Audition

7128-453: The volume dangerously high to compensate, at the risk of causing hearing loss . 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 or rubber pads for comfort. (The use of the term earbuds , which has been around since at least 1984, did not hit its peak until after 2001, with

7216-692: Was Nathaniel Baldwin. He was the first major supplier of headsets to the U.S. Navy . In 1910, motivated by his inability to hear sermons during Sunday service, he invented a prototype telephone headset. He offered it for testing to the navy, which promptly ordered 100 of them. Wireless Specialty Apparatus Co., in partnership with Baldwin Radio Company, set up a manufacturing facility in Utah to fulfill orders. These early headphones used moving iron drivers , with either single-ended or balanced armatures. The common single-ended type used voice coils wound around

7304-519: 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 1958, John C. Koss , an audiophile and jazz musician from Milwaukee , produced the first stereo headphones. Smaller earbud type earpieces, which plugged into the user's ear canal, were first developed for hearing aids . They became widely used with transistor radios , which commercially appeared in 1954 with

7392-489: Was developed by the British company Electrophone . The device created a listening system through the phone lines that allowed the customer to connect into live feeds of performances at theaters and opera houses across London. Subscribers to the service could listen to the performance through a pair of massive earphones that connected below the chin and were held by a long rod. French engineer Ernest Mercadier in 1891 patented

7480-430: Was mounted on the head by a clamp which held it next to the ear. The head mount freed the switchboard operator's hands, so that they could easily connect the wires of the telephone callers and receivers. The head-mounted telephone receiver in the singular form was called a headphone . These head-mounted phone receivers, unlike modern headphones, only had one earpiece. By the 1890s a listening device with two earpieces

7568-449: Was rather short lived, however, use of the process continued well into the mid-1970s on promotional records sent to radio stations. Many commercial FM Rock stations did not transition from mono to stereo broadcasting until the mid to late 1970s. AM Pop music stations continued to broadcast in mono, as AM stereo broadcasting was not introduced until 1982 and was never widely adopted. Many promotional singles and some commercial singles from

7656-439: Was the beginning stage of radio broadcasting . Some early wireless telegraph developers chose to use the telephone receiver's speaker as the detector for the electrical signal of the wireless receiving circuit. By 1902 wireless telegraph innovators, such as Lee de Forest , were using two jointly head-mounted telephone receivers to hear the signal of the receiving circuit. The two head-mounted telephone receivers were called in

7744-400: Was used primarily from about 1968 until 1970 but still exists on a significant number of recordings made during the time. The Haeco-CSG process was designed to make stereophonic vinyl LP records compatible with mono playback equipment. These recordings were intended to make the two-channel stereo mix automatically "fold-down" properly to a single mono channel. The reason for the process

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