The directional response is the manner in which the microphone responds to sounds coming from different directions. The directional response of a microphone is usually recorded in a polar diagram. This diagram shows the level of pressure "perceived" by the microphone coming from all angles, in different frequency bands.Generally, this does not depend on the type of construction of the microphones, but in most cases, the form of construction can influence the outcome and the type of that microphone polar pattern.The polar pattern of a microphone can determine its use for different applications. Below we have different types of polar diagrams of microphones.CardioidSupercardioidHypercardioidFigure 8 or bidirectionalOminidirectionalThe omni-directional microphones pick up sound from all directions, so roughly equal. Both work equally well when pointed away as pointed in the direction of the subject, if the distances are equal. However, even the best omni models tend to become directional at higher frequencies, so the sound coming from behind may seem a bit "dull" than what lies ahead, although it seems equally "loud. "The physical size of the omnidirectional microphone is directly related to the maintenance of its omnidirectional characteristics at very high frequencies. The body of the microphone simply blocks the shorter wavelengths of high frequencies that come from behind. Therefore, the smaller the microphone body diameter, the more it can become truly omnidirectional. ShotgunDirectional microphones are specially designed to respond better to sounds that lie ahead (and behind, in the case of bi-directional), tending to reject sound coming from other directions. This effect also varies with frequency, and only the better microphones are able to provide uniform rejection over a wide frequency range. This directional ability is usually the result of external openings and internal passages in the microphone that allow sound to reach both sides of the diaphragm so carefully controlled. The sound coming from the front of the microphone will help move the diaphragm, while the sound coming from the side or rear will cancel movement. Example Supercardioid The stereo recording techniques are used when we want to register and / or reproduce the feeling of space that surrounds our auditory perception of an acoustic event. All elements must be considered, since the reproduction of images side and center, passing through the sense of depth or distance and even the acoustic feeling of involvement with the environment, which is usually represented by reverberation. Surround makes this experience even more real and has the help of psychoacoustic effects mainly caused by lags.There are four main groups of techniques:Coincident pair (X, Y, M and S-Blunlein)Spaced pairs (A / B, 3x1, Deca Tree)Coincident pair almost (ORTF)Artificial Head (Dummy Head) X-YThis technique requires two identical directional microphones, usually cardioid. The capsules should be very close - preferably overlap - that can turn forming angles between 90 and 130 . When fitted properly, the result of the sum to mono must suffer an increase of up to 6 dB in signal amplitude, without phase cancellation.M-SIt also consists of two microphones, a directional points at the center toward the sound source and another, Figure 8 with its