The directional characteristic indicates the sensitivity of a microphone as a function of the angle of incidence. Reference is the 0 axis as the main sound source. The directional characteristic is illustrated by directional diagrams. The directional characteristic is not the same over the entire frequency spectrum, but varies according to the frequency. Therefore, in the directional diagrams, the characteristic is uniformly displayed at 1 kHz. In principle, it can be said that the directional characteristic is significantly less pronounced at low frequencies than at high frequencies.
There are two main directional diagrams once the sphere characteristics and the kidney characteristics.
In the sphere characteristic, the sound is received in the same direction from each direction, so the term omni directional is often used.
On the other hand, in the case of the kidney characteristic, only the sound is converted from the front. On the rear axes (180 °) there is theoretically an almost 100% extinction, apart from reflections. In practice, the attenuation is about 20-35dB. The renal characteristics of a microphone are often referred to as uni directional.