The working principle of the headset is that the left and right cores of the headset are wound with coils, and then fitted with two small pieces of iron, which will vibrate with the magnetic strength. As the coils are connected to the audio output connector, the headset receives the electrical signals from the media player or receiver, and utilizes the speakers close to the ear to convert them into audible sound waves.
The impedance of a headphone is the sum of the DC resistance of the coil and the inductive resistance of the coil. Civilian headphones and professional headset impedance are generally below 100Ω; headset sensitivity is applied to the headset on the 1mW of electric power, the headset produced by the coupling in the simulation of the ear (dummy head) in the sound pressure level, 1mW of power is based on the frequency of 1,000Hz when the headset's standard impedance as the basis for calculation.
Expanded Information:
Headphones are categorized based on their driver type and how they are worn.
1, moving coil type
It's driver unit is basically a small moving coil speaker, by the voice coil in a permanent magnetic field to drive the diaphragm vibration connected to it. Moving coil headphones are more efficient, mostly for audio on the headphone output driver, and reliable and durable. Generally speaking the larger the diameter of the driver unit, the better the performance of the headphones.
2, moving-iron
Dynamic-iron headphones can be easily placed in the ear canal because the unit is much smaller. This effectively reduces the area of the in-ear portion of the ear can be placed into a deeper portion of the ear canal. The geometry of the ear canal is much simpler than that of the auricle, and is circular in shape, so a soft silicone sleeve provides good sound isolation and prevents sound leakage.
3, isomagnetic
Isomagnetic headphones driver is similar to a scaled-down planar speaker, it will be a flat voice coil embedded in a thin diaphragm, like a printed circuit board, you can make the driving force evenly distributed. The magnets are concentrated on one or both sides of the diaphragm (push-pull), and the diaphragm vibrates in the magnetic field it creates. Isomagnet headphone diaphragms are not as light as electrostatic headphone diaphragms, but have the same large vibration area and similar sound quality.
Baidu Encyclopedia - Headphones
Baidu Encyclopedia - Principle of Headphones