horn
　　Can refer to an electroacoustic component, the role is to convert electrical signals into sound, also known as speakers.
　　This kind of interaction between the magnetic field and the horn coil causes the energy of the electronic horn coil to move forward at any time Change to produce sound.
　　Phonation mode
　　Moving coil
　　The basic principle comes from Fleming's left-handed law. If a wire with electric current and magnetic line of force are vertically placed between the north and south poles of the magnet, the wire will move due to the interaction of magnetic line of force and electric current. When a diaphragm is attached to the wire, the diaphragm will move forward and backward with the change of electric current. At present, more than 90% of the cone basin monomer are dynamic coil design.
　　Electromagnetic
　　A movable iron chopper (armature) is set in the middle of a U-shaped magnet. When the current flows through the coil, the armature will be magnetized and the magnet will produce the phenomenon of attraction and repulsion, and drive the diaphragm to move at the same time. This kind of design is cheap but ineffective, so it is often used in the telephone barrel and small earphone.
　　Inductive
　　It is similar to the electromagnetic principle, but the armature is doubled, and the two voice coils on the magnet are asymmetric. When the signal current passes through, the two armatures will push each other for different magnetic flux. Unlike electromagnetism, inductance can regenerate at a lower frequency, but its efficiency is very low.
　　Electrostatic
　　The basic principle is Coulomb's law, which is usually treated by vacuum vaporization of plastic film and aluminum and other inductive materials. The two films are placed face to face. When one of them is applied with positive current and high voltage, the other one will induce a small current. By mutual attraction and repulsion, the air will be pushed to produce sound. Due to its light weight and small vibration dispersion, electrostatic monomer is easy to get clear and transparent mid and high pitch, which has no control over the power of low pitch. Moreover, its efficiency is not high, and it is easy to collect dust when using DC. At present, manufacturers such as Martin Logan have successfully developed a hybrid loudspeaker with static and dynamic coils, which solves the problem of insufficient bass of static body and is widely used in earphones.
　　Plane type
　　The voice coil design, which was first developed by Sony in Japan, is still the theme of moving coil design. However, the cone basin diaphragm is changed into the honeycomb structure plane diaphragm, because of the few people cavity effect, the characteristics are better, but the efficiency is also low.
　　Ribbon style
　　Without the traditional voice coil design, the diaphragm is made of very thin metal, and the current flows directly into the channel body to make it vibrate. Because its diaphragm is voice coil, it has very light weight, excellent transient response and high frequency response. However, the efficiency and low impedance of ribbon horn have always been a great challenge to the expander, which can be represented by apogee. Another way is to have a voice coil, but the voice coil is printed directly on the plastic sheet, which can solve some of the low impedance problems. Magnepang is a leader in this kind of design.
　　Horn
　　The diaphragm pushes the air at the bottom of the horn to work, because the sound is not diffused during transmission, so the efficiency is very high. However, because the shape and length of the horn will affect the timbre, it is not easy to replay the low frequency. Now most of them are used in giant pa systems or treble units. Klipsch of the United States is an old horn manufacturer.