1、 How are headphones classified
1. According to the principle of energy exchange
There are mainly three types of earphones: dynamic, balanced armature and electrostatic.In addition to these three categories, there are still several isomagnetic earphones, but they have been eliminated or used for professional purposes. The market share of HI FI is very small, so I will not discuss it here.
Moving coil earphone: at present, most earphone earplugs belong to this category. The principle is similar to that of ordinary speakers. The coil in the permanent magnetic field is connected with the diaphragm, and the coil drives the diaphragm to produce sound under the driving of signal current.
Moving iron earphone: also known as balanced armature, it was originally used for hearing aids.The moving iron unit can make the diameter smaller, so as to design the earphone with greater depth in and out of the ear.
Electrostatic earphone: the diaphragm is in the changing electric field. The diaphragm is very thin and accurate to several microns. The coil drives the diaphragm to make sound under the driving of electric field force.
2. According to the structure of earphone cavity
It is mainly open, semi open and closed (closed).
(1) Open style: Generally speaking, it has a natural sense of hearing and comfortable to wear. The hifi earphone, which is commonly used at home, can leak the sound, otherwise,it can also hear the external voice. The earphone has less pressure on the ear.
(2) Semi open: there are no strict regulations, and the sound can only be in and out, and the corresponding adjustment can be made according to the needs.
(3) Closed type: the ear muff has great pressure on the ear to prevent the sound from coming in and out.The sound is correctly positioned and clear, which is common in the field of professional monitoring.
2、 Earphone related parameters
In the world of direct current (DC), the effect of objects on current is called resistance,but in the field of alternating current (AC), in addition to resistance, capacitance and inductance will also hinder the flow of current. This effect is called reactance. What we call impedance in daily life is the vector sum of resistance and reactance.
The sound pressure level (the unit of sound pressure is decibels, the higher the sound pressure,the greater the volume). Therefore, the higher the sensitivity and the smaller the impedance, the easier the earphone will sound and drive.
The sensitivity value corresponding to the frequency is the frequency response, and the image drawn is the frequency response curve.The range of human hearing is about 20hz-20000hz. At present, the mature earphone technology has met this requirement.
3、 Terminology of sound quality evaluation
Range: the range between the highest and lowest pitch of an instrument or human voiceTimbre: also known as timbre, one of the basic attributes of sound, such as Erhu and pipa, are different timbres
Sound dye: the opposite of natural and neutral music, that is, the earphone sound is infected with some characteristics that it does not have. For example, the sound obtained by speaking to a jar is a typical sound dye.
The sound dye indicates that there are more (or less) components in the replayed signal, which is also a kind of distortion.
Distortion: the output of the equipment cannot completely reproduce its input, resulting in waveform distortion or increase or decrease of signal components.