The devices for sound reproduction were originally primitive electromagnetic telephones. The creation of the first telephone is traditionally attributed to Alexander Graham Bell, who in 1876 patented a device for transmitting sound, the principle of which formed the basis for the design of headphones.
Headphones, phones and more
In fact, all headphones are arranged the same, if any differences exist, then they are more likely associated with the elements of the device and the materials used, but not with the structural scheme.
Thus, any earphone is designed, like everything ingenious, quite simple. First of all, this is a kind of housing in which an electromagnetic device is fixed, consisting of a coil, a flexible membrane and a permanent magnet.
The coil is usually a specific frame that is attached to a flexible membrane. The frame has a winding of thin copper wire, and the resistance of this winding must comply with a certain standard. It should be between 20 and 120 ohms. Recently, a transition to the 50 - 600 Ohm standard has been planned in the world.
An alternating voltage is supplied to the terminals of this coil from a source of sound vibrations.
The permanent magnet is located inside the coil, and a guaranteed gap is provided between it and the coil itself, which allows the coil to move freely along the axis. When a signal arrives at the terminals of the coil in the form of an alternating voltage modulated by the frequency of sound vibrations, a corresponding alternating magnetic field is induced in the coil, which, in turn, interacting with the constant magnetic field of the magnet, causes the membrane to vibrate, since the latter is rigidly fixed to the coil frame.
Headphones are far from simple
This is how almost all headphones for phones are arranged, but at this stage other differences begin. And they are significant enough. So, for example, the quality of the sound is influenced by the purity of the copper from which the wires are made, and the quality of soldering of the contacts, and the presence of gilding on the contact pairs, and if we talk about the symmetry of the headphones, then in the top models they are calibrated and selected almost manually, than and the extremely high price is due.
The headband brace also attracts the attention of headphone manufacturers. This seemingly uncomplicated device experiences constant variable loads, moreover, it must provide optimal coverage and the necessary, and at the same time, comfortable compression.
Separate words are deserved by special headphones for computer games, which are already equipped with three speakers for each channel, have a subwoofer simulator and transmit sound through the front, rear and side channels.