What Causes Feedback From A Microphone

Screeching. Howling. Whistling. Singing. These are all unpleasant sounds that you may have had the misfortune of hearing when dealing with microphones. Audio feedback is a common occurrence in the world of onstage events and recording venues.

But that doesn’t mean you have to deal with it.

By understanding what feedback is, and what causes audio distortion to occur from a microphone, you can learn how to eliminate it and prevent those nasty sounds from picking up again.

Audio feedback is no silent menace; it can be quite loud, and may cause damage to the ears if it persists for too long.


The Larsen Effect

Understanding audio feedback is simple:

When a loop occurs between a source of audio input and a source of audio output, this can cause positive feedback. This positive feedback has many names, including audio feedback, acoustic feedback, the Larsen Effect, or simply “feedback”. All of these terms define the same event, one that celebrities and event hosts are all-too-familiar with.

Some examples of an audio input includes:

  • Microphones
  • Guitar pickups
  • Recording devices

While the source of audio output may be:

  • Monitor
  • Loudspeaker
  • Computer

When these devices interact with each other, it has the potential to cause an auditory loop. This looping can build up the longer it exists, causing the whirring or screeching sound that causes guests to cover their ears and scowl at the stage.


Common Occurrences

If you’ve heard audio feedback in the past, you were likely at some sort of live event, or near a speaker system. This is where audio feedback problems are most likely to occur, considering that these events require some sort of sound reinforcement or projection system to reach auditory clarity. PA systems and speakers are mandatory in large facilities or on stages, as it’s the only way that the entire audience can receive a clear auditory sound. However, this can also be problematic for the rejection of feedback.

It’s not fair to give audio feedback an entirely bad rap, however. There are some cases where audio feedback can be a good thing.

Do you like heavy metal music?

A lot of popular rock bands will intentionally distort their sounds and cause feedback from their guitar amplifiers in order to create a desired effect. This has been a favored process since the days of Jimi Hendrix and the early Rolling Stones. Since then, the genre has flourished on its trademark feedback sounds and sustained audio loops from various recording devices.


How to Stop Audio Feedback

Investing in a cardioid microphone is highly recommended in order to prevent audio feedback from occurring. While it does not guarantee to scrub all sounds 100% of the time, it operates on a unidirectional system that will only pick up the sound of your voice, while rejecting sounds from the sides and rear of the mic.

Pair this with an automatic feedback detection device, which has been a popular development for the past few decades. These devices can buffer and reduce the amount of auditory feedback that is likely to occur during your event.

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