A bi-directional microphone, often referred to as a "figure of eight", is a type of microphone that picks up sound with equal sensitivity from the front and back. On the other hand, sound coming from the sides, i.e. from 90 degree angles, is almost completely suppressed. It gets its name 'figure of eight' from its directional characteristic, which is a graphical representation of the microphone's sensitivity to sound from different directions, and this graph does indeed resemble a lying figure of eight. This characteristic makes it suitable for specific situations, such as recording a conversation between two people sitting opposite each other at a table, where one microphone is enough for both. Similarly, it is used to record two musicians or singers standing opposite each other. This type of microphone is also part of some stereo recording techniques, where it is combined with other microphones to create a surround sound image. Because it also picks up the sound from the other side, it captures not only the direct sound source, but also the reflections and atmosphere of the room, which can add natural space to the sound.
