How to avoid Microphone Feedback

Posted by AudioMart on January 3rd, 2020

How to avoid Microphone Feedback

Acoustic feedback occurs when the microphone picks up audio from the loudspeaker and transmits it back into the amplifier. A Loop occurs which builds in intensity and produces Microphone Feedback. This is usually due to the volume being too high or the microphone too close to or in front of the speakers, Feedback will not stop until you break the loop by turning down the microphone.

Every venue has a point where feedback cannot be avoided.

First method in reducing Microphone Feedback is for the singer to use the microphone correctly

If the singer is holding the microphone too far away from his mouth, then you have to turn the PA system up louder to compensate and you will induce feedback. The singer should not be touching the wire at the top of the microphone as the vents that create the cardioid pickup pattern get covered and causes feedback.

Avoid using cheap microphones

Cheap microphones are more prone to feedback.

Place your speakers in the correct position

Your speakers must be positioned in front of the line of your microphones. Try moving your speakers forward to reduce feedback. If the performer cannot hear the music on stage, consider purchasing stage monitors. Try angling the PA speakers differently even slightly changing the angle of the speakers can affect feedback enormously.

Isolate which microphone is causing the problems and change the EQ settings Feedback occurs at varying frequencies. You may be able to adjust the EQ on the mixer to cut down the feedback.

Use the correct type of microphone for the application

(Information source: https://www.audiomart.co.za/index.php/pro-sound-equipment-microphones-c-1_6)

Omni-directional microphones pick up as much sound from behind as well as in front of the microphone. Cardioid, Super Cardioid, Rifle microphone pickup patterns are much better for stage use though you should be aware of the drawbacks with each type. For example, Super Cardioid pickup patterns might reject sound from the back very effectively, but they are also very susceptible to handling noise and tend to emphasise "P" and "B" consonants explosively through the sound system, especially when used close to the mouth.

Consider the natural room acoustics

Establish what the natural room acoustics are like, try shouting loudly or clapping. If there is a basic echo in the room, then you may be fighting a losing battle. If there are curtains or drapes, try closing them to reduce the amount of natural reflections you get. Feedback at sound check time when you do your sound check, the room will be empty and cooler than when you actually play. Bodies absorb sound and cold rooms make feedback worse. You may therefore be able to cope without the feedback when you are actually on stage.

Are you using wireless microphones?

Wireless microphones are more prone to feedback as the singer is free to move around the stage and possibly move in front of the speakers. Use your sound check to establish the working area for your wireless microphones.