How To Prevent Audio Feedback

31 Band EQ to prevent feedback

This 31 band EQ can be used to prevent feedback.

Different spaces can make presentations and live audio extremely hard to work with. Echoes, sound-absorbing fixtures and irregular architectural shapes can ruin the way sounds reach the attendees’ ears. This can leave audiences with a bad impression of the content or production you’re trying to deliver. Fortunately, we’ve picked up quite a few handy tricks over the years that let us perfectly equalize (EQ) any sound system and eliminate dreaded feedback.

What is Feedback
Everybody’s heard it before, but feedback is the technical term for what happens when a microphone can “hear” the sound waves coming from the speakers. This creates a loop, where the usually quiet signal from the microphone picking up background noise is amplified by the speaker. Then the microphone picks it up again and the speaker re-amplifies it. This process continues many times per second, culminating in a horrible, generally high-pitched whine coming out of the speakers at tremendous volume.

Although feedback has been used deliberately to create cool sounds in pop music, it has no place in our clients’ meetings, conferences or events. Unwanted feedback is distracting, annoying, and can potentially damage the hearing of those who are in the room.

Dealing with Feedback
There are plenty of ways to handle feedback, but they all basically involve interrupting the loop that causes it. You can:

  • Keep sensitive microphones (lapel mics, podium mics) remain behind the speakers at all times.
  • Use less sensitive microphones with a tighter diaphragm
  • Use EQ techniques to prevent amplification of frequencies that are likely to cause feedback

 

EQ’ing a room to prevent feedback
Of course, no EQ’ing is complete without testing. When we setup a sound system for a client, we usually start by playing a familiar song so we can hear how that song sounds in the room that we are using. We will then turn down (or up) various frequencies on our EQ system to make the song sound good in the room.

Then, we’ll usually place a microphone at or instrument pickup at the front of the room and intentionally turn it up until it begins to feedback/squeal. Once it starts to feedback, we go back to our EQ system and manually turn down the frequency that seems to be squeeling. This process of “ringing out” microphones and instrument pickups let our technicians figure out just which pitches are traveling through the space and then adjust those sliders on their multi-frequency soundboards appropriately, allowing maximum volume with minimum noise.

Professional Expertise
It’s important to realize that although we’ve made these tricks seem pretty simple, EQ’ing is an involved process. Some of the feedback spaces generate isn’t detectable by the human ear until it’s too late and the presentation has already begun. Our technicians have years of experience dealing with feedback using advanced detection equipment and we’d love to help you make sure your presentations, performances and recording sessions come out perfect.

If you have any questions, or are interested in having Kettner Creative run Sound or A/V at your next event, please contact us for more information.