# What causes "flare" when testing audio equipment?

**URL:** <https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718>\
**Category:** Factual Questions\
**Created:** [January 14, 2019, 2:20am UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718 "2019-01-14T02:20:40Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\
**Post date:** [January 14, 2019, 2:20am UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/1 "2019-01-14T02:20:40Z")

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When people are testing audio stuff at concerts, what causes that sudden deafening “flare” of noise? (Hard to put in words)

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**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\
**Post date:** [January 14, 2019, 2:38am UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/2 "2019-01-14T02:38:38Z")

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Do you mean audio feedback? It’s caused when a mic picks up audio from the speakers and the gain is large enough that it re-amplifies itself and goes out of control.

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**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\
**Post date:** [January 14, 2019, 2:50am UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/3 "2019-01-14T02:50:20Z")

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Ah yes that, thanks.

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**Author:** ![Kiwi\_Fruit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kiwi_fruit/32/12_2.png) [@Kiwi\_Fruit](https://boards.straightdope.com/u/Kiwi_Fruit)\
**Post date:** [January 14, 2019, 9:08pm UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/4 "2019-01-14T21:08:04Z")

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> [@Velocity](#):
>
> When people are testing audio stuff at concerts, what causes that sudden deafening “flare” of noise? (Hard to put in words)

The word I use is SQUEAL!

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<div class="post-metadata">

**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\
**Post date:** [January 14, 2019, 9:21pm UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/5 "2019-01-14T21:21:31Z")

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> [@Kiwi\_Fruit](#):
>
> The word I use is SQUEAL!

Well, in this instance, it wasn’t the squeal though. It was a sudden increase in acoustic vibration, in such a way that it made your whole body (and especially the gut) just have this uncomfortable “resonance” vibration flutter inside. Very potent.

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**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\
**Post date:** [January 14, 2019, 9:35pm UTC](https://boards.straightdope.com/t/what-causes-flare-when-testing-audio-equipment/827718/6 "2019-01-14T21:35:21Z")

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I’ve heard that called whalesong. Our audio system was being tested to its limit and nobody was allowed in the theater/meeting room, but we could hear it from the control room (probably the whole building).