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Arizona Bay
05-18-2015, 09:41 AM
I've wondered about this phenomena for years. When you take a cup of hot black coffee, add sugar to it and begin to stir it, the pitch of sound of the spoon hitting the side of the cup, rises. What is happening here?

Ian McColgin
05-18-2015, 09:44 AM
Better ear than mine but it's likely related to increasing the specific gravity of the coffee to better absorb the lower overtones of the ding on the china, leaving the higher ones to reach your ears.

TerryLL
05-18-2015, 09:46 AM
Anticipation of the suger-coffee jolt causes the inner ear to spasm. Basically, the change in pitch is all in your head.

Paul Pless
05-18-2015, 09:53 AM
anticipation of the suger-coffee jolt causes the inner ear to spasm. Basically, the change in pitch is all in your head.




:d ...

ron ll
05-18-2015, 10:06 AM
I always thought it had to do with the temperature of the spoon increasing. But if the spoon expands with heat, seems like the pitch would get lower. Dunno.

Figment
05-18-2015, 10:14 AM
The spoon expands because the heat energy excites the molecules, etc... does the embodied energy change the transmission of the sound?

Edited to add.... of course, there is no spoon but for the purpose of this discussion

Bruce Taylor
05-18-2015, 10:26 AM
From the American Journal of Physics: The Hot Chocolate Effect (http://escholarship.org/uc/item/9dh21770#page-3)

Jim Mahan
05-18-2015, 10:28 AM
I have noticed the effect and supposed it was due to the density or viscosity of the coffee being slightly affected as the sugar melts and blends in.* But it is also partly the organizing effect of the swirling current generated by the spoon. Organizing the flow may influence the propagation of sound vibrations. Notice the difference in the effect between regular coffee and a nuked cup of joe. Nuking makes it sound very hollow.

*The same as when basaltic lava, which is thin and flows readily, becomes thickened and flows more slowly mixed with sand, mostly felsic quartz.

Arizona Bay
05-18-2015, 10:31 AM
I think the cup would be the source of the tone, modified by the coffee, and the questionable spoon is just the striker, so I'm not sure if the size of the spoon matters.


TerryLL (http://forum.woodenboat.com/member.php?15155-TerryLL)
[/quote]

http://forum.woodenboat.com/images/icons/icon1.png Re: Coffee Related Science Question.

Anticipation of the suger-coffee jolt causes the inner ear to spasm. Basically, the change in pitch is all in your head.




A Pavlovian response and Quantum entanglement! :D

Arizona Bay
05-18-2015, 10:44 AM
From the American Journal of Physics: The Hot Chocolate Effect (http://escholarship.org/uc/item/9dh21770#page-3)

Wow, 26 pages. I'll give this a read, after coffee.

Arizona Bay
05-18-2015, 10:48 AM
I have noticed the effect and supposed it was due to the density or viscosity of the coffee being slightly affected as the sugar melts and blends in.* But it is also partly the organizing effect of the swirling current generated by the spoon. Organizing the flow may influence the propagation of sound vibrations. Notice the difference in the effect between regular coffee and a nuked cup of joe. Nuking makes it sound very hollow.

*The same as when basaltic lava, which is thin and flows readily, becomes thickened and flows more slowly mixed with sand, mostly felsic quartz.I wonder if the microwaves are affecting the cup itself and changing the tone?

CWSmith
05-18-2015, 12:11 PM
This is really interesting!

Flying Orca
05-18-2015, 12:31 PM
Sound travels faster as the density of the fluid medium increases.

P.I. Stazzer-Newt
05-18-2015, 03:54 PM
Neatly explaining what happens to your voice on Helium.......

Bruce Taylor
05-18-2015, 06:28 PM
Further investigations into the Hot Chocolate Effect: The Instant Coffee Effect (http://www.kilty.com/coffee.htm).

http://i282.photobucket.com/albums/kk273/BruceDSTaylor/coffee1_zpswyn7gtdm.gif

Keith Wilson
05-18-2015, 06:48 PM
According to both articles, it's the bubbles . The coffee or hot chocolate starts foamy with lots of small bubbles, then as it's stirred the bubbles rise to the top and escape. The pitch rises a bit and the sound quality changes from dull to more ringing, making the sound a lot brighter, which seems higher. Seems plausible.

Bruce Taylor
05-19-2015, 06:15 AM
According to both articles, it's the bubbles .

Exactly. I haven't tried it, but apparently you can model the effect with a glass of water and an Alka Seltzer tablet: Bubbles that Change the Speed of Sound (http://www.researchgate.net/profile/Eugenia_Etkina/publication/258706656_Bubbles_that_Change_the_Speed_of_Sound/links/00b495293be063bed3000000.pdf).

skuthorp
05-19-2015, 06:38 AM
What happens if the spoon bowl is made of sugar?

P.I. Stazzer-Newt
05-19-2015, 10:20 AM
A spoon bowl of sugar helps the medicine go down?

Arizona Bay
05-19-2015, 10:38 AM
This morning I tried saturating the sugar in the spoon before stirring it, didn't notice any pitch change when I did stir it.
Might be the bubbles, or could be lack of coffee before the experiment. :D

Bruce Taylor
05-19-2015, 11:49 AM
This morning I tried saturating the sugar in the spoon before stirring it, didn't notice any pitch change when I did stir it.
Might be the bubbles, or could be lack of coffee before the experiment. :D

That seems consistent with the "bubbles" theory, and neatly rules out the possibility that the solute itself changes the pitch by increasing the density of the fluid.

My guess is that pre-saturated sugar is unable nucleate gases suspended in the beverage. Suspended gases typically nucleate on solid surfaces, and powders are known to cause nucleation. The ability of some substances (https://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption) to cause rapid nucleation has been entertaining the internet for more than a decade. :D


https://www.youtube.com/watch?v=hKoB0MHVBvM

TomF
05-19-2015, 11:55 AM
Standing ovation.

Can you begin to imagine how sticky they were after all that?

David W Pratt
05-19-2015, 12:14 PM
This clearly calls for further research with beer, and Guiness

Waddie
05-19-2015, 12:19 PM
Wow..... you can think about stuff like this before you've had that first cup of coffee. I can't even remember what day it is before my coffee in the morning, much less think about what the spoon is doing.

regards,
Waddie

TomF
05-19-2015, 12:30 PM
This clearly calls for further research with beer, and GuinessI'm not letting anyone get close to a decent beer ... let alone Guinness ... with a package of Menthos. :D

John of Phoenix
05-19-2015, 12:48 PM
Further investigations into the Hot Chocolate Effect: The Instant Coffee Effect (http://www.kilty.com/coffee.htm).

http://i282.photobucket.com/albums/kk273/BruceDSTaylor/coffee1_zpswyn7gtdm.gif
I have a modified application or this gizmo but first to establish the need. Has anyone else noticed that on Monday mornings (especially Mondays), your computer seems to be a bit sluggish? Slow to boot, slow to load programs, slow to switch pages, slow to load web sites, etc.? I've heard several people comment on this phenomenon.

If the sensor ABOVE the coffee was immersed IN the coffee, could it possibly provide a caffeine jolt directly to the BIOS, CPU, NIC, RAM and HDD?