This microphone has been designed to suppress the disturbing ambient noise as much as possible. Only the user's language should be transmitted loudly and clearly. This goal is achieved by the fact that the noise cancelling microphone has at least one input opening, on the front and back. In the middle of these openings, the membrane is fixed inside the microphone. The sound that comes from the environment hits the membrane through the two openings almost simultaneously. As a result, only a very small deflection of the membrane takes place. On the other hand, sound waves from a very short distance (1-3 cm) cause a stronger deflection of the diaphragm and thus generate an electrical pulse. The reason is that the sound from the front at a short distance rather reaches the diaphragm than the sound through the rear opening. Hence, on the one hand there is no compensation and on the other hand the sound pressure dominates from the front and provides thus provides a stronger signal.
