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Omnidirectional microphones Magnetic, ceramic, and electret microphones are omnidirectional microphones that accept the same amount of sound in all directions. Currently, electret microphones are widely used in the field of acoustics and are made of an insulating, permanently polarized material. The sound enters the microphone, and the density change of the sound wave causes the negative metal diaphragm to vibrate, and then the sound energy is converted into mechanical energy, and the diaphragm vibration generates pressure on the host body and is transmitted to the rear plate of the electret. Both the electret rear plate and the bottom of the diaphragm are connected to the field effect transistor preamplifier and have a terminal to the outside. When the diaphragm vibrates, the distance and space between the diaphragm and the electret rear plate changes, generating a voltage, and the mechanical energy is converted into electric energy through a field effect transistor fixed on the microphone, and then transmitted to the amplifier through the terminal. The electret microphone has a wide frequency response, high sensitivity and durability, and the diaphragm is the only part of its motion.

Directional microphones are classified according to the form of polarity, and the sound coming from the front is much more sensitive than the sound coming from behind. The directional microphone has two openings at the ends of the diaphragm, one on each side. The vibration of the diaphragm depends on the phase relationship and depends on the pressure difference at both ends. A fine acoustic filter is placed on the front end of the rear sound hole to delay the sound, so that the sound from the back can reach the diaphragm from both front and rear sound holes and cancel, so the polarity of the directional microphone is in the shape of a heart. .

This kind of pointing is named after its heart is like a heart: in front of the microphone, its sensitivity to the audio signal is very high; and to the side of the microphone (90 degrees), its sensitivity is good, but It is 6 decibels lower than the front; in the end, it has a very good shielding effect for the sound from behind the microphone. It is because of this shielding effect on the sound behind the microphone that the heart-shaped pointing microphone is very useful in a multi-recording environment, especially when it is necessary to eliminate a large amount of indoor ambient sound. In addition, the microphone can also be used for live performance because its shielding function can cut off the echo and ambient noise generated during the performance. In practice, the cardioid pointing microphone is also a relatively high-usage type of microphone, but keep in mind that, like all non-omnidirectional microphones, the heart-shaped pointing microphone will exhibit a very pronounced proximity effect.

This type of pointing is very similar to over-cardioid pointing and is often confused, but the general supercardioid pointing type is slightly less directional than the over-cardioid, and its sensitivity to the sound from the back of the microphone is also small. Much more.

This type of pointing concentricity is very similar to supercardioid pointing because they are very sensitive to the sound in front of the microphone. However, their lowest sensitivity is at a different point. For example, the heart shape is directly behind the microphone, the supercardioid is at 200 to 210 degrees, and the overcardioid is at 150 to 160 degrees. That's why the directionality of the heart-shaped pointing microphone is better than that of the heart-shaped pointing and super-cardioid pointing microphones. In practice, such over-cardioid microphones are often used in recording environments that require maximum isolation of the source.

This type of pointing microphone, as its name suggests, is equally sensitive to audio signals from all directions around the microphone. The biggest advantage of this type of microphone is that it does not produce significant proximity effects.

Sometimes, it is also called a bidirectional shape, because this type of microphone has the same high sensitivity to the audio signal from the front and the back of the microphone, but is less sensitive to the signal from the side of the microphone, so that it picks up The sound range is presented on the drawing, which is like an 8 word, and the position of the microphone is just at the 8 word cut point, hence the name.