Monday, 13 June 2022

HEAD PHONE TECHNOLOGY



                                   
                                                      HEAD PHONE TECHNOLOGY



    Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears.
Headphones are also known as earspeakers, earphones. Circumaural 'around the ear' and supra-aural 'over the ear' headphones use a band over the top of the head to hold the speakers in place. Another known as earbuds or earpieces.  Other are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open.Headphones connect to 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.
  The first headphones were developed in the late 19th century. 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 a cable. 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 1/4 inch (6.35mm) or 1/8 inch (3.5mm) phone jack for plugging the headphones into the audio
source. These early headphones used moving iron drivers, with either single-ended or balanced armatures. The common single-ended type used voice coils wound around the poles of a permanent magnet, which were positioned close to a flexible steel diaphragm. In early powered radios, the headphone was part of the vacuum tube's plate circuit and carried dangerous voltages. In 1958, John C. Koss, an audiophile and jazz musician from Milwaukee, produced the first stereo headphones. 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.
  Headphones are available with high or low impedance (typically measured at 1 kHz). Low-impedance headphones are in the range 16 to 32 ohms and high-impedance headphones are about 100-600 ohms. 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. A modern pair of headphones is driven by an amplifier, with lower impedance headphones presenting a larger load. 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 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.
  Headphones with soldered headphone jack cables. Wireless on-ear headphones. Often has an inbuilt headphone jack. Wireless over-ear headphones. Often has an inbuilt headphone jack. ireless earphones
connected via a neckband.True wireless earbuds have no cord to keep each bud connected to each other. They rely on wireless technology such as Bluetooth to transmit audio from a hardware device. Supra-aural headphones or on-ear headphones have pads that press against the ears, rather than around them. Earphones are very small headphones that are fitted directly in the outer ear, facing but not inserted in the ear canal. 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. 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.
  A headset is a headphone combined with a microphone. Headsets provide 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. Telephone headsets connect to a fixed-line telephone system. A telephone headset functions by replacing the handset of a telephone. 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 pin-alignment similar to a telephone headset adaptor, but it also offers sound amplification for the microphone as well as the loudspeakers. Communication headsets are used for two-way communication and typically consist of a headphone and attached microphone. Such headsets are used in a variety of professions as aviation, military, sports, music, and many service-oriented sectors.
  Headphones use various types of transducer to convert electrical signals to sound. 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. 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. 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. Planar magnetic (also known as orthodynamic) headphones use similar technology to electrostatic headphones, with some fundamental differences. 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.
 
  Headphones can prevent other people from hearing the sound, either for privacy or to prevent disturbing others, as in listening in a public library. 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. It is possible to change the spatial effects of stereo sound on headphones, to better approximate the presentation of speaker reproduction, by using frequency-dependent cross-feed between the channels. 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. 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 low-efficiency, high-impedance equipment, while the same amount of power can reach dangerous levels with very efficient earphones.Hearing risk from headphones' use also applies to workers who must wear electronic or communication headsets as part of their daily job like call center and dispatch operators, sound engineers, firefighters and hearing damage depends on the exposure time.


 

                                                                    



                                                                   



               

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HEAD PHONE TECHNOLOGY

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