Why you can hear the temperature of water
nytimes.com
nytimes.com
One group (me included) enjoys some levity, as long as it's high quality and doesn't get in the way of substantial discussions.
Another group would prefer that HN avoids that entirely.
It mostly seems like a matter of taste / preference, so I'm not sure how we can come to one kind on this, shy of seeing the pro-humour approach clearly hurting the site.
Not sure how much of this would be complimentary to the acoustic effect of temperature. Either way, it’s not a simple single-solution explanation.
[0] https://wisconsindot.gov/Documents/doing-bus/eng-consultants...
I'm sure piano techs are all over this topic, but (as a layman) I could imagine the wood's water content being quite relevant.
A piano soundboard that has been built and kept in a desert for instance will not crack. But if you take a piano from a ~55% humid country and put it in a desert (or overly air-conditioned room! or right in front of a heat radiator!) it will die.
The one harp I've seen up close was in an upright piano I disassembled, and that harp was solid.
Here you can see a soundboard, bridge, and hitch pins on the harp. The hitch pins on the harp can be seen up top, then in the middle the bridge and bridge pins, and then below that the soundboard. The hitch pins are located on the opposite side of the keys in a grand, or on the bottom of the piano in an upright. You can see on the right of the image that the harp has a structural element which floats over the bridge, with plenty clearance.
https://www.chuppspianos.com/wp-content/uploads/2014/03/Stei...
P.S. In some pianos you can really hear a metallic undertone produced by the harp, I find Yamaha pianos have a distinct sound that has it.
most of the US is too dry in the home, and humidification is helpful for all wood in your home - to a point of course. Approx 55% is optimal
Of course in the south it’s the exact opposite - but A/C usually solves the problem.
Every homeowner should monitor their indoor humidity, it’s important for, wood floors, door trims, wood furniture, and our own health. Too much causes mold, too dry is hard on your respiratory system
You can try it yourself. Take two identical kettles, boil the water in each of them and pour it somewhere. Obvious difference.
But the creek will ring like a bell. You can't hear it until you're almost on top of it. It's higher pitched, and will almost always have a tempo based on the shape of the bed of the falls.
There's a waterfall on our farm. It plays music in January. It's amazing, and no one believes me.
That just makes me wonder how many other things there are that people subconsciously learns, without it ever becoming obviously noticeable for them?
Another example is frame rates: while its well known that the bandwidth of light sensitive cones on the retina is around 30Hz cycle frequency (and thus ~60Hz framerate), many gamers felt the difference of higher framerates, even though many of the same gamers denied observability of this difference on the basis of knowledge of this basic biological fact.
The biological fact is not wrong: if screen pixel projects are at rest on the retina. But when the eye is rotating to follow a depicted object on the screen, then speeds higher than ~60 pixels per second result in motion blur that would be absent when observing a real life object moving at the same angular speeds. The biological fact is still true, but simply not naively applicable in the context of motion blur due to eyeballs rotating while observing a display.
You can't actually say that human eye has a strict fps, so the higher screen fps the less weird interactions with the ugly hacks in our brains.
Mitigating sample and hold motion blur by blacking out the display for some of the frame time turns your display into a flickering light source, so it can potentially produce the same effect for small bright objects on dark backgrounds when either the object moves rapidly on screen or you scan your eyes across the screen. It's fairly niche in that it'd only affect some rather specific scenes and even then can depend on how the scene is viewed (it won't occur if you track the only fast-moving bright object with your eyes, and it's much reduced in higher ambient light), but the flicker fusion rate is generally several kilohertz, so you'd need to boost the hell out of the frame rate to guarantee the effect is eliminated altogether.
More generally, an object that is moving rapidly enough for its screen position to change by many pixels per frame can have its motion look jerky even without motion blur. And, in fact, motion blur can help disguise that.
Is there a way to sync the monitor’s refresh rate to a different phase/offset?
It would be cool to play with that setting and see the effects on our perception of the screen
Our eyes are good at adapting to all kinds of things - like really small red, green and blue lights in an array can look like anything to us
About turning the screen on and off, it’s very slow if I want to change it in real time. It would be nice to have a little nob on the side and just change the phase one way or the other in correspondingly :)
Just because you can see it doesn't mean others can.
its extremely easy to reproduce, and I have not encountered anyone who fails to see it once told how to reproduce it:
suppose your screen is 1920 pixels wide (Full HD). suppose a patter contains high spatial bandwidths, i.e. high spatial resolutions like text.
obviously if a monitor is able to display say at a 60 Hz frame rate, then motion blur would be essentially absent if the font bitmap is moved 1 pixel per frame, or at least the motion blur would be constrained to 1 pixel of horizontal blur.
to traverse about 1920 pixels from the left side of the screen to the right at 1 pixel per frame (or 60 pixels per second) would take 32 SECONDS. Half a minute!
consider much faster velocities, say 3 seconds for a word to move from the left side of your screen to the right, thats motion blur such that a pixel is blurred the length of 10 pixels! Most people would not consider this very fast at all.
now take note of the DPI of the screen and print the same text at the same dimensions on paper, and hold it up close to your screen, and move it from left to right in about 3 seconds, while following it with your eye. You wont see motion blur on the real piece of paper, but you will on the digitally rendered text of same dimensions and velocity...
once you understand this phenomenon, you will understand in what sense the flicker bandwidth of human retina at rest with respect to a visual stimulus should not be confused for a sufficient framerate to accurately reproduce the perception of visual stimuli representing motion, unless the backlight is strobed at a very low duty cycle. but then flicker becomes visible again unless we bump the framerate up a notch again.
The guy says "Baa" and we see his lips move accordingly. Then we hear him say "Baa" again, but this time he's obviously pronouncing something else, judging by his lip movements. We don't know what he's saying (or at least those of us without lip-reading skills don't), but nothing unusual or tricky seems to be happening.
What am I missing?
95%+? Stuff like how to jiggle keys on a keyring to get the right one for the door you're about to unlock? This only works for your keyring, it's highly kinetic, tactile, initial condition dependent etc, yet yet can usually be done unconsciously IME with the 6 keys on my keyring.
We can’t consciously tell, but they can see our brain lighting up when sensing the changes
Link to video: https://youtu.be/dg3pza4y2ws?si=-yXtwIu2n4QR_1Wi
You're absolutely right that people ignore whole lot going on around them in terms of sound, smell etc.
So often worth fixing even if you don't worry about getting a shock.
To counteract the noise, you attach a (special, you'll see "Y") capacitor between the primary and secondary sides, right next to the transformer. Now that high frequency noise sees an "easy" short-circuit and it is contained in a small loop within the power supply, not leaking out into the outside world. This needs to be much larger than the (very small) transformer capacitance so it dominates that system.
The downside of this is that now you have an appreciable capacitance between the primary and secondary side. In a grounded system, you connect the primary side of that big capacitor to ground and everything is fine. In an ungrounded system, you can only connect it to something referenced to one of the two wires you have: line or neutral. This means that a small current will flow into the capacitor from each side at line frequency (50 or 60Hz) and the secondary side, connected to the case, will float at some appreciable fraction of mains voltage. You, a damp meatsack, prodding the secondary side with your fleshy protruberances, have capacitance as well. So when you touch this case, that's floating at AC voltage around 100-200V (depends where you are in the world) there's a small current that flows between you and the case as well as the charge flows back and forth. This is what you feel via your nerves, which can detect miniscule currents in this range. Because the capacitors linking you to the mains are, in an absolute sense, small (though far larger than the transformer capacitance), the current is limited to a small amount, far under a milliamp. Actually this would still happen without the bigger capacitor, as there's already some capacitance there, but it could only provide an imperceptible current even to the bio-miracle of the human nervous system. So you have to balance EMI reduction (more capacitance better) against this sensation (more capacitance makes it more noticeable and eventually with a really huge capacitance it would be its own safety hazard).
Why a special capacitor? Well, if were to fail to a short between primary and secondary, now your isolated case is not isolated, it's connected directly to the mains supply and there's no earth wire to dump current to and blow the RCD. So if it didn't immediately blow the fuse (and even then, it needs many 10s of amps to do that to the whole circuit if you don't have fused sockets or plugs in your country, and even then it can also set itself and things nearby on fire without blowing a fuse using only an amp or two if you're unlucky) because it's sitting on, say, metal earthed desk, it's now still floating at mains voltage. However, now it won't deliver microamps, it can deliver a lot more though that carbonised previously-a-capacitor-now-a-small-resistor. If you touch it and have a decent connection to ground, instead of the interference with pacemakers, it can become a turbocharged pacemaker, but your heart doesn't work so well at 50/60Hz and may object to this by going on strike. Regulators for some reason think this is a problem, so you use a special safety capacitor called a "Y" or "X" type, depending on exactly how you use it, which is designed to satisfy them that you probably won't discontinue anyone's sinus rhythm or burn down a building (even if they've actually consented by buying your product!)
So, while is this not an intentional effect, it's also an calculated aspect of the power supply design in the absence of an earth wire and is not a sign of a defect or danger. Other than reminding you that the only thing between you and mains voltage is insulation that's carefully specified, regulated and tested to be safe, for some standardised definition of "safe", of course.
You can also see a much stronger version of this effect with a plasma globe (remember them?). The frequency and the voltage is much higher than 50Hz mains, but the principle is the same: the sphere surface is isolated plastic, there's a very small capacitance to the coil. The current flowing in the low pressure gas in the void is what makes the tendrils. With your with your hand on it, you float at very high voltage and can even produce a tiny sub-millimetre, continuous spark to other objects as the small current flows back and forth into this small capacitance. In retrospect, that plasma globe probably has questionable EMI behaviour when doing that!
Given that one of the devices in question was a Mac Mini (which did indeed have a two-prong plug without earthing), I wonder why Apple didn't put in a little more effort to give consumers an earthed plug. There's more than enough margin on their devices, and computer-like appliances normally have grounded plugs here anyway (Netherlands).
Unearthed two-prong plugs are slightly more convenient here because they fit in more sockets. But I'd prefer earthing over that small convenience.
Adding an earth conductor would require a thicker, less flexible 3-wire cable, a bigger plug (in the countries that have the option of a 2-pronger) and a three-pin power connector if it's not a captive cable, which is bigger and heavier. To ground that Y capacitor node means taking the earth conductor from the socket to near the SMPS transformer, and you have to maintain strict clearance and creepage distances between that conductor and the live/neutral regions at all points. Modern power supplies are very compact, so this is actually more of an ask than you might expect.
As the device is already designed to meet or exceed safety requirements without the earth wire, all it does is avoid the tingle and add weight, volume, design effort and component cost. As mass market devices produced by the hundreds of millions, this is not deemed a good tradeoff.
You can avoid this on your own, however, by grounding the case yourself, by connecting any exposed metal to a local earth point. Remember that Macs are anodised, so the surface isn't really conductive, (which actually amplifies the effect at the point of contact as a thin insulator is also a capacitor!).
> Unearthed two-prong plugs are slightly more convenient here because they fit in more sockets.
That argument doesn't work here, all are 3 pin. It's a conducting third pin too, even though it's NC, which isn't even compliant.
My suspicion is that it's way more noticeable on European voltages (frequency could also be a factor?) so they don't notice in the US and don't care. I have a few products that do it; they're all US companies except one Japanese (slightly lower than US even at 100v, and product primarily sold to US I suspect).
My Framework laptop will shut down if it touches a charging but un-Earthed MacBook.
That you can feel artificial lighting as heat (the actual light, demonstrated as it was a laser some distance away) at such a low power level (<5mW) was pretty surprising to me.
My mind wants to immediately look directly at the perturbations at an almost instinctive level. If I do look I frequently see a leaf moving in the wind or a bird or squirrel moving around in the tree.
By intentionally using this effect rather than actively scanning the forest I find I am much better at finding birds when bird watching or seeing larger animals such as foxes, deer, or snakes moving in the grass.
It's amazing how many things our bodies are capable of that we don't know about until we step away from electronics and machinery and just let the body do its thing.
I thought I'd heard the 'stickiness' of the water affects how it sounds. Not sure if that is stiction or something else.
Viscosity isn't something I considered... but it makes sense.
Includes raw recordings as well as actual raw results for those of us without NYT subscriptions.
https://osf.io/brp2a/?view_only=7f49783ebbf646b29af32ca64524...
Audio comparison video, the fun part for me anyway.
https://osf.io/brp2a/files/osfstorage/62fe7d9da06acd0f5b2db3...
Google AI tells me:
"The Finnish word narskua translates to "crunch" or "scrunch" in English. It's an onomatopoetic verb that describes the sound snow makes when you step on it in very cold temperatures"
1) We actually can sense "coldness" or "hotness" as separate tastes. Think about mint candies or pepper for example.
2) Our receptors have different sensitivity based on the temperature. For example cold sweet drink feels much less sweet. That's why warm cola is disgustingly sweet for example.
And water does contain a lot of dissolved salts which have a taste.
3) More than half of the taste we feel is actually coming from the smell, and warm water contains more vapour, and therefore, more smell.
So our brain takes all these inputs from different sources and synthesises the feeling of taste in our brain.
Source of this knowledge is from: https://www.cookingforgeeks.com
https://static.nytimes.com/podcasts/2024/05/09/science/09tb-...
Probably the 2 basslines from the first samples (cold) was something that bothered the dog, maybe the thing is in rich sound such as chord vs single note. I don't care about bubbles but when I will have an access to a nice microphone I will try to record more samples of this. The hard part is how to remove water from the glass between 2 or more experiments because it is important to have really similar setups without moving the glass even slightly.