# The sounds of a kettle

**URL:** <https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593>\
**Category:** Factual Questions\
**Created:** [October 7, 2006, 7:15am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593 "2006-10-07T07:15:15Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\
**Post date:** [October 7, 2006, 7:15am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593/1 "2006-10-07T07:15:15Z")

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Why does the kettle get louder and louder as the water heats up, and then goes completely silent _just_ as the water starts to boil (and before the whistling starts)?

I’ve noticed this recently, because my night shifts are slow enough that I can actually sit and watch the kettle boil. No paint drying, you see - gotta do something.

I know why it _whistles_ - steam escaping that little opening. But the louder-and-louder-until-silence thing is driving me nuts. Help?

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**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\
**Post date:** [October 7, 2006, 8:41am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593/2 "2006-10-07T08:41:03Z")

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I believe it’s caused by cavitation. Tiny bubbles form in the water, however since the vapor pressure isn’t higher than the air pressure the bubbles collapse before they reach the surface. The sound you hear is the bubbles collapsing. As the temperature rises, more and more bubbles are formed and collapse, making it louder. However, when it reaches boiling, the bubbles reach the surface instead of collapsing, so the pot gets quieter.

Or (dang, searched AFTER typing that), [in The Master’s own words.](http://www.straightdope.com/classics/a2_115a.html)

(At least I know now why I know that fact.)

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**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\
**Post date:** [October 7, 2006, 9:01am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593/3 "2006-10-07T09:01:38Z")

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Dammit, and I searched, too.

Thanks, **Turek**.

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**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\
**Post date:** [October 7, 2006, 9:40am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593/4 "2006-10-07T09:40:30Z")

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[QUOTE=Antigen]  
Dammit, and I searched, too.

Thanks, **Turek**.  
[/QUOTE]

NP, it was the highlight of lying in bed at 4am not being able to sleep. \<sigh\>

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**Author:** ![Spidey](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@Spidey](https://boards.straightdope.com/u/Spidey)\
**Post date:** [October 8, 2006, 2:31am UTC](https://boards.straightdope.com/t/the-sounds-of-a-kettle/375593/5 "2006-10-08T02:31:40Z")

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Well **Turek** , if its any consolation, you’ve helped me as well. I’ve boiled many tea kettles in my day and I’ve always wondered about this. You’ve done me a great service. Sleep well.