Audio feedback is a sound problem that can happen with microphones, speakers, and sound systems. It is the loud, annoying noise that sometimes happens when a microphone gets too close to a speaker. The noise can sound like a loud squeal, screech, or whistle.

Audio feedback happens when the sound from a speaker goes back into a microphone over and over in a loop. This makes the sound get louder and louder very fast until it hurts people’s ears.

How audio feedback happens

Audio feedback happens when a microphone picks up the sound coming from a speaker, and that sound goes back into the speaker again. Then that louder sound goes into the microphone again, and back into the speaker even louder. This keeps happening over and over, getting louder each time. That is why the noise gets so loud so fast.

The audio feedback loop

Here is how the audio feedback loop works:

1. The microphone hears the sound from the speakers
2. The sound goes from the microphone into the sound system
3. The sound system makes the sound louder
4. The louder sound plays through the speakers
5. The microphone hears that louder sound and the cycle starts over

Each time the sound goes through this loop, it gets louder. After a few loops, the sound gets painfully loud. The sound system is basically turning up its own volume over and over.

What makes audio feedback more likely to happen

Audio feedback is more likely to happen in certain situations. Some of the main things that make feedback happen more easily are:

Microphones pointed at or near speakers

If a microphone is pointed right at a speaker, the sound can very easily go straight from the speaker into the mic. This makes a feedback loop happen quickly. Even if the mic is not pointing right at the speaker, if it is too close, feedback is more likely. The sound doesn’t have to travel as far to get back to the mic and start the loop.

The volume is turned up too high

When the volume of the sound system is too loud, any sound that gets into the mic will be amplified a lot. This strong, amplified sound is more likely to get picked up by the mic again and start a feedback loop. The louder the overall volume is, the easier it is for feedback to start.

Bad sound system setup

If the speakers and microphones in a sound system are not set up well, feedback is more likely. Sound systems should be set up so the mics are as far from the speakers as possible. In good setups, the speakers are also in front of the mics, not behind. If mics are in front of or above speakers, sound can go right from the speakers into the mic.

How to stop audio feedback

When audio feedback starts, it is important to stop it quickly. The loud noise can hurt people’s ears and even damage the sound equipment. There are a few ways to stop feedback:

Turn down the volume

The first thing to do is turn down the volume right away. This makes the sound quieter so it is less likely to get picked up by the mic again. With the volume lower, the feedback loop is broken.

Move the microphone or speaker

If the mic is too close to the speaker, moving it farther away can stop the feedback. Pointing the mic away from the speaker also helps. Sometimes moving the speaker farther from the mic or turning it so it doesn’t point at the mic works too.

Use a feedback eliminator

A feedback eliminator is a device that can be added to a sound system. It listens for the start of feedback and quickly lowers the volume at those frequencies to stop the noise. Feedback eliminators can help a lot in spaces where the mics have to be close to the speakers.

Preventing audio feedback

The best way to deal with audio feedback is to stop it before it starts. Good sound system setup and careful mic placement can prevent most feedback. Here are some tips:

Keep mics far from speakers

The more distance between mics and speakers, the better. If they have to be close, try not to point mics right at speakers. Use feedback eliminators in problem spaces.

Do a soundcheck

Before an event, do a soundcheck. Have someone talk into or sing into the mics while you listen for feedback. Slowly turn up the volume until feedback starts. Then back off the volume a bit. Mark those levels so you don’t go past them during the event.

Use directional mics

Directional mics pick up sound better from in front than from the sides or back. Using directional mics pointed away from speakers can help a lot. Omnidirectional mics that pick up sound from all around are more likely to cause feedback.

Watch the volume

Don’t turn the volume up too high, especially if you hear feedback start. Keep the volume just loud enough for the space you are in. If you need it louder in some areas, use more speakers spread out rather than turning it up too much.