Can You Hear Temperature?

In this video I do some experiments to see if you can tell the temperature of things by the sound they make. I also show you why your voice gets higher when you inhale helium.

[frankkkk]

You can definately hear temperature: If it's cold outside, I always hear my mom complaining about it.

[TheActionLab]

At 4:42 I meant to say the “less dense” a gas is the faster sound moves, not “the more dense”

[MeFreeBee]

A few years ago I attended a lecture by a member of the Primary Thermometry team at the UK's National Physical Laboratory. He was explaining their work on creating an acoustic thermometer which measures temperature through the speed of sound in a gas and is so accurate that it has been used to help measure the Boltzmann constant to greater precision than ever before. It is also being used to check the accuracy of the International Temperature Scale.

[MrKotBonifacy]

8:58 - My dad used to tell me about particularly cold winters in Central Europe during WWII and in the years just after it - temperatures reached as low as -40°C (same in °F), and one could hear trees "exploding" from freezing in the forest during the night (he lived in some village back then). "And then on one night", he said, "I've heard some people talking 'next to me' but there was no-one around! - it kinda spooked me, and I looked around, further away and saw two guys talking, but they were like well over hundred metres away from me!".

[jigpu]

Finally! An explanation of *why* helium's faster speed of sound changes pitch! Changes of resonance! Bravo!!

[willdabeastro]

My theory would have been that the steel shrinking also changes the geometry of the fork, thereby changing its natural frequency - sweet video!

[spencer]

I remember in marching band we always had to tune to the vibrophone when it was cold because it would be sharp compared to a wind instrument who would be flat.

[Dudleymiddleton]

8:09 That Helium stuff is magic - it makes you look younger as well as talk like Chip 'n' Dale! lol

[chrism]

Growing up in Minnesota, I can tell you that commercial jets flying high above sound higher pitched in the dead of winter than in summer. Like adjusting the tone knob to treble in winter and to bass in summer. As far as actual temperatues, I'm talking -10F to 90F(-23c to 32c). I don't know what combination of effects causes that, but I notice it every year.

[yeroca]

It's really great how you covered so many effects in such a short video. All very clearly explained! Thanks!

[rollomaughfling]

Thank you for explaining how our voices might _appear_ to be higher with a lighter gas, but it's only a higher _timbre, _ due to harmonic emphasis, and the pitch stays the same. Veritasium got this dead wrong in a whole-ass lecture a few years ago, and I've barely forgiven Derek for it. Like people mistaking dwarfs' voices as higher-pitched, when—no, they just have a smaller cavity in which their vocal cords vibrate. I've simulated many "children's choir" parts for tv shows _as a natural baritone, _ and while one does need to pitch them up a bit (smaller vocal cords) it's no more than two hundred cents or so, and it's all about the pitch/formant balance to achieve a convincing effect. Anyone who's even played around with a professional pitch modulator plugin in the last 20 years knows this, which is what was so frustrating about Derek's lecture.

[YoungGandalf]

A caution to any visitors to The Action Lab: Do not drink from the insulated thermos, it does not contain coffee.

[Solesteam]

2:00 I think I can guess why, it's how the molecules do much less moving so the sound waves are shorter since it's rushing back to it's original position much faster, the hotter one, with much more movement leniency won't be so strictly held in place making it able to wiggle and move further creating larger waves.

[DarthMirasshtar]

If you are a blacksmith, you can totally hear temperature

[redplanet]

Super interesting. That water pour blew my mind.

[imdawolfman]

You rarely cease to amaze me, by dissecting the things I (we) take for granted and demonstrating the miraculously fine tuning our senses, and perceptions, have evolved for us.
And demonstrating how numb we have let our brains become by hating each other for irrelevant reasons, like skin color or political leanings.
Thank you.

[johnr]

Yes, you can. As the weather cools, you can hear far more sounds outside. Just listen to cars. You can hear them much farther away in cold weather.

[Zithorius]

I was gonna say that for all 3, it won't matter because I can feel my eardrums and thus I can 'hear' most differences in temperature but the explanations you gave were 10/10. Then that 5 picometer nugget at the end iced the cake.

[mike.]

3:47 is when sponsor ad ends. I hope they paid you really good for this one, because that's one of those horrible games that everybody sees fake mini game ads for and nobody actually wants to play!

[IronBrain]

Vocal cords acoustically loaded like a loudspeaker. In other words, the “spring” in the spring mass oscillator that is your vocal includes the air flowing through it. So the vocal cords actually resonate at higher frequencies in helium. You sound weird and not just higher pitched because there is still air ( and other stuff ) throughout our nasal cavities, and so there is a mismatch between the excitation frequency and the resonances in your head.