How to eliminate the acoustic feedback in a sound equipment?
The acoustic feedback occurs when the microphone picks up the signal from the loudspeaker itself that reproduces its sounds. The sound then "turns" on a closed circuit causing a loud whistle. To eliminate the feedback there are several techniques. The first consists in using directional microphones that pick up the sound of the desired direction, eliminating the possibility of picking up the sound of the speakers that should be properly positioned. The second is to move the speakers as far as possible from the microphone. Finally we have circuits that can help solve the problem. One is a phase inverter that is connected to the input of the amplifier. By reversing the phase of the captured signal, we can reduce the effect of the microphone. Finally, there are sophisticated circuits like those that use common mode signals for the reproduced signal and the microphone signal so that they cancel and even lines of delay or digital processing of the signal.
