Headphones are the symbol of people's personal sound. There are two standards for mobile phone headphones: OMTP standard is usually called national standard, and CTIA is called international standard. Headphones are classified according to their energy conversion modes, mainly including moving coil mode, moving iron mode, electrostatic mode and equal magnetic mode. According to the structure and function, it can be divided into semi-open type and closed type; From the wearing form, there are ear plug type, ear hanging type, in-ear type and head wearing type; Judging from the number of people wearing it, there are single-person headphones and multi-person headphones; From the sound source, it can be divided into active headphones and passive headphones; Active headphones are also often called plug-in headphones.
The price range of headphones is 50-tens of thousands of RMB, the ordinary price is generally around 20 RMB, and the slightly better price is around 100 RMB. If it's headphones, the price is usually higher. The price of top headphones, such as limited edition headphones produced by some top brands, can reach tens of thousands of RMB or more. The above is the price in the physical store, if it is in the online store, the corresponding price is slightly lower.
Headphones are classified according to the type of drivers (sensors) and the way they are worn.
Moving coil type
Moving-coil earphone is the most common earphone, and its driving unit is basically a small moving-coil loudspeaker, which is driven by a voice coil in a permanent magnetic field to vibrate the diaphragm connected to it. Moving-coil headphones are efficient, and most of them can be driven by headphones in audio, which is reliable and durable. Generally speaking, the larger the diameter of the driving unit, the better the performance of the earphone. At present, the largest diameter of the driving unit in consumer headphones is 50mm, which is generally the flagship earmuff.
Moving iron type
It is an earphone which is conducted to the center of the miniature diaphragm through a connecting rod with a precise structure, so as to generate vibration and sound. Moving iron headphones can be easily put into the ear canal because the unit is much smaller. This effectively reduces the area of the ear part and can be placed in a deeper ear canal part. The geometric structure of the ear canal is much simpler than that of the auricle, and it belongs to a quasi-circular shape, so the soft silicone sleeve can play a very good sound insulation and sound leakage prevention effect compared with the traditional earplugs.
Isomagnetic type
The driver of equipotential headphones is similar to a reduced flat speaker. It embeds a flat voice coil into a thin diaphragm, which can make the driving force evenly distributed like a printed circuit board. Magnets are concentrated on one side or both sides of the diaphragm (push and pull), and the diaphragm vibrates in the magnetic field it forms. Isomagnetic earphone diaphragm is not as light as electrostatic earphone diaphragm, but the vibration area is the same and the sound quality is similar. Headphones without moving coils are efficient and difficult to turn on.
Electrostatic type
Electrostatic headphones have a light and thin diaphragm, which is polarized by a high DC voltage. The electric energy required for polarization is converted by alternating current and also provided by battery. The diaphragm is suspended in an electrostatic field formed by two fixed metal plates (stators). Electrostatic headphones must use special amplifiers to convert audio signals into voltage signals of several hundred volts and drive them. The sound pressure level it can achieve is not as high as that of the dynamic earphone, but it has a fast response speed and can play back all kinds of tiny details with very low distortion.
electret
Electret headphones are also called fixed electrostatic headphones. The diaphragm itself is polarized or polarized by the electrostatic field emitted by the polarized substance outside the diaphragm, and no special equipment is needed to provide polarization voltage. Electret headphones have most of the characteristics of electrostatic headphones, but electret will gradually depolarize and need to be replaced, and its service life is about 5- 10 years.
Wireless cordless
They are composed of two parts, the signal transmitter and the earphone with signal receiving and amplifying device (usually moving coil type). The transmitter is connected to the signal source, and the front stage or earphone amplifier can be connected in front of the transmitter to improve the sound quality and adjust the timbre.
Wireless headphones generally refer to earphone systems that transmit signals through infrared rays, while cordless headphones refer to earphone systems that transmit signals through radio waves. The working frequency of infrared headphones ranges from several KHz to several MHz, and the effective distance is about 10 meter. Headphones should be in the visual range. The working frequencies of radio headphones are VHF 130MHz-200 MHz and UHF 450 MHz -900MHz. Most cordless headphones work at UHF, and the transmission range is 100m, which can bypass obstacles. Two or more pairs of wireless/cordless headphones may interfere with each other, so it is best to choose a variety with multiple working frequencies when choosing. For cordless headphones, working under UHF, it is less likely to be interfered by VHF. Both headphones have background noise, and the higher-end models use noise reduction technology. It should also be noted that the battery life of wireless/cordless headphones should generally not be less than 8 hours.
At present, the advanced wireless headphones adopt Bluetooth 3.0 transmission with aptX technology, which can provide advanced CD-like audio via Bluetooth.
Because it is too close to yourself, it is ignored. Headphones are such products. In real life, headphones can be seen everywhere, whether at home or outdoors, all kinds of English listening tests, etc., are indispensable. Headphones have been developing continuously with the progress of people's science and technology since their invention.
With the development of time, earphone products have gradually matured from the first two small speakers hanging in the ear. No matter the type of earphone or the way of wearing it, or even the core pronunciation unit, many changes have taken place.
Dressing style
The earliest earphones were two pronunciation units hanging on the ear, and later many kinds were developed, including earphones, earplugs, ear hooks and newly developed bone conduction earphones. Headphones are the earliest types of headphones.
Earplugs are a revolutionary breakthrough in the development of headphones, and the smaller size makes it very convenient to use outdoors. Due to the development of the city, the environmental noise is getting louder and louder. In-ear earplugs are a breakthrough in earplug products and are more suitable for outdoor use.
Earhook can be regarded as an intermediate product of earphone and earplug. The characteristics of the ear hook neutralize the advantages and disadvantages of headphones and earplugs, and belong to a product with unclear characteristics, but it is very beautiful to wear. Bone conduction earphone is a relatively new technology, which uses the principle of vibration to transmit sound directly to the listening center through the skull. However, this product has not been popularized, and it is still unknown whether it can bring revolutionary breakthroughs to headphones.
Variety
Because of the different uses of headphones, the types of headphones are gradually enriched. The types of headphones can be roughly divided into open, closed and semi-open.
Open headphones generally feel comfortable to wear. Comfort here means no sultry feeling, which is common in HIFI headphones enjoyed at home. Sound can leak out, on the contrary, external sound can also be heard, and the earphone has less pressure on the ear.
There are no strict rules for semi-open headphones, and the sound can only enter but not exit. The design can be adjusted according to the needs of use.
The earmuffs of closed headphones are fully enclosed, which can prevent external sounds from entering, and have a strong sense of oppression on the ears, and the sound positioning is accurate and clear. This structure is often used in the field of professional monitoring. There are also some closed headphones that have the sound field of open headphones, which can isolate noise and still maintain high quality sound.
With the development of headphones, the most important pronunciation unit is dynamic pronunciation unit. After so many years of development, the technology of dynamic headphones has been very mature, but it has also encountered the bottleneck of sound improvement. In addition to electrostatic headphones, there are many derivative technologies of dynamic pronunciation unit, among which dynamic pronunciation unit is the most widely used.
The moving iron sounding unit generates an alternating magnetic field by using an electromagnet, and the vibrating part is an iron piece suspended in front of the electromagnet. When the signal passes through the electromagnet, the magnetic field of the electromagnet will change, thus making the iron plate vibrate and sound. Its advantages are long service life and high efficiency. Disadvantages are large distortion and narrow frequency response. Often used in early telephone receivers. This technology is now mainly used in earplugs. Because the moving iron pronunciation unit is much smaller than the moving coil pronunciation unit, many high-end earplugs integrate two or even three moving iron pronunciation units, and the sound performance in each frequency band is excellent.
The diaphragm is suspended in an electrostatic field formed by two fixed metal plates (stators), and the electrostatic earphone must use a special amplifier to convert the audio signal into a voltage signal of several hundred volts.
Although electrostatic headphones have various benefits, the technology of this pronunciation unit is only in the hands of a few manufacturers, and the basic price of electrostatic headphones on the market is more than 10 thousand yuan. It is worth mentioning that WINNY, an earphone enthusiast in China, developed the first electrostatic earphone in China, which became a landmark earphone in the history of earphone development in China.
Headphones are developing towards wireless and noise reduction. Wireless headphones are more free to use. With the development of science and technology, wireless transmission technology has gradually matured, ensuring the sound quality of wireless headphones. Another reason is the popularity of mobile phone music function and the birth of Bluetooth wireless transmission technology, and Bluetooth wireless headphones have developed rapidly.
With the increasingly serious noise pollution in the city, using ordinary headphones and earplugs outdoors can only increase the volume to cover up the noise, so that you can't enjoy wonderful music, and it will also have a great impact on your hearing. The emergence of noise-reducing headphones has solved this problem well.
Active noise reduction headphones have a noise reducer, which uses a microphone to collect external sounds and emits opposite sound waves to cancel the noise. Today, people are more and more concerned about their health. Noise-reducing headphones can enjoy music better outdoors and ensure the health of ears, which is the development direction of headphones in the future. Active noise reduction headphones are specially designed for travelers, which have the characteristics of wireless, noise reduction and high sound quality. Bluetooth 3.0 with aptX can provide up to 10 hours of music listening.
Technology can only transmit information conveniently by radio signals, so mobile phone radiation is inevitable. Mobile phone is a very strong radiation source, especially the power at the moment when the phone is connected. Long-term frequent phone calls can even cause sudden death. Because the intensity of radiation is inversely proportional to the square of distance, keeping distance is the most effective in the application of preventing mobile phone radiation. The basic principle of anti-radiation headphones is to close the distance between the human brain and the mobile phone. If you violate this principle, you can't really play a role in radiation resistance.
At present, there are two kinds of headphones used in mobile phones that can prevent radiation, Bluetooth headphones and air-guided headphones, among which air-guided headphones have better effect. The air-conducting earphone developed by Chinese scientific and technical personnel has obtained the invention patent of the International Bureau of the World Intellectual Property Organization (PCT) (the international patent application number is PCT/CN2009/000660 and the international publication number is WO 201043097A1). This is the first time that the International Bureau of the World Intellectual Property Organization has awarded the invention patent to the radiation-proof earphone products of mobile phones, which proves the outstanding advantages of air-guided earphones in radiation protection of mobile phones.