Headphones were invented in the 19th century. Since then, they have been greatly improved and various form factors have emerged as well. Nevertheless, the principle of their work remained the same.
Instructions
Step 1
Headphones are based on emitters. The most popular emitter configuration is dynamic, with a moving coil. The permanent magnet is permanently attached to the headphone housing and creates a static magnetic field. Magnets can be ferrite (in cheaper models) and neodymium. In this magnetic field, a coil of wire is located, through which an alternating current modulated by a sound signal passes. When the current in a conductor changes, the surrounding magnetic field also changes.
Step 2
A thin membrane is fixed on an elastic suspension, and a coil is attached to it. The latter moves due to the interaction of the constant field from the magnet and the alternating field from the coil. The membrane begins to vibrate due to the movement of the coil. This vibration is transmitted through the air, and the ear perceives it as sound. The sound largely depends on what material the diaphragm is made of. It can be a synthetic polymer film in cheaper models; cellulose, mylar and other materials in mid-range headphones and titanium in more expensive devices.
Step 3
This scheme is used in almost all modern headphones of various form factors. Dynamic emitters also have a number of disadvantages. So, due to the relatively low speed of reaction to a change in sound, the membrane is often unable to reproduce low and high frequencies equally well. This problem is especially true for "liners" and "inserts". Therefore, there were models of dynamic headphones with two emitters. Another problem is the unevenness of the magnetic field where the coil moves. This makes the sound somewhat unpredictable and unstable. For this reason, some other emitter schemes were invented, with their own advantages and disadvantages.
