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Aleksandr Berdnikov
Registrace 6. 03. 2022
Double splash experiment
Threw 2 pebbles in a lake, the overlapping waves from them form this neat pattern
zhlédnutí: 948
Video
Eastern red bat
zhlédnutí 2,6KPřed rokem
Yeah, I know, it neither enjoys being woken up nor being touched, really. But a few seconds of this kind of bothering wouldn't harm it.
Acoustic interference (flying over our heads)
zhlédnutí 59KPřed rokem
Unusual physics in mundane events. My pacing may be off sometimes, so be welcome to pause, etc. Thanks to czcams.com/users/3blue1brown for the impetus that #SoME2 has given me. 0:00 The question 0:17 Doppler hypothesis 1:10 Spectrogram 2:00 Echo interference 3:25 Verification 5:22 Double slit analogy 7:14 But where's Doppler? 8:06 Recap
Circular polarization from Japanese Beetle's carapace
zhlédnutí 313Před rokem
Many scarab beetles have carapaces that consist of layers of fibers, whose direction rotates from layer to layer. That makes it highly reflective for the matching circular polarization and wavelengths of light (a-la Bragg mirror), giving it distinctive metallic appearance. Light of the opposite polarization passes pretty much as usual, revealing black pigment below the mirror layer. Here I swit...
Tea vapor and convection cells
zhlédnutí 295Před 2 lety
The gap lines on the fog layer (blue) coincide with the boundaries of convection cells (visible in red due to refraction jaggedness)
It started to fall asleep! 😭😭😭
❤❤❤❤❤❤🦇
Did you use the 3b1b animation package to do this video or was it something else. Very high quality!
No, I was too lazy to learn it (though might have been easier to do so, idk). I've made frames with Wolfram Mathematica, and pulled them into a video with ffmpeg. As you might guess, I'm not quite a professional) Thanks for your comment though.
The is the single cutest thing I have ever seen
OMG That is so cute! 😍🦇
Basically a flying fluffy sausage.
I LOVE BAAAAATSS❤❤🦇🦇🦇
Lol the description. He/she didn't seem to mind xD So cute.
Why ru scared of misgendering a bat 😭 it ain't gonna hurt u 😭
@@ClodsireBcuzYes Hello Sir. I did not know his/her gender. Usually I just say "it" or "they" when I don't know. shrug
I've heard the Doppler effect as a jet passes overhead, but never noticed that- yeah, wow- there is a frequency component that rises after the aircraft has passed. 3blue1brown called attention to this (by referring to this very video) and I was really blown away by listening closely to the sounds. I still hear the dominant sound of the decreasing frequency, but thanks to you I also became aware of the rising frequency. Very cool, and thank you for the explanation!
I'm really glad to hear it, getting others to share the "aha!" moments in understanding the nature is really satisfying:)
The sympathetic vibrations of the sheet metal that make up the underside of the wings mostly occur in the lower frequency range. This sound is mostly directed at right-angles to the surface of the metal. I think this is contributing to the effect, if not dominating it. (Lay down on the ground to see if the effect persists, to verify.)
Even if there is a contribution from such effect, it's not the stripy pattern that kinda dominates the spectrogramm. I've checked what you suggested, and couldn't hear the pitch going back up, only the Doppler lowering; so - no, I don't think so.
god i was trying to find this video a couple months ago thank god i found it
Human's propensity to pet literally creature with fur is astonishing 😂
Living in a very quiet house with only a few white noise sources, I can sympathize with the author, who discovered this while walking past an AC unit. I always figured "ok it is weird reflections (from the shape of the room?)", but this is way more detailed and useful! It is indeed "weird reflections" but based on angle and distance! Very cool video, thank you!
Yeah, in a closed room it becomes more complicated with multiple reflections and complex geometry. For example, it is fun sometimes to walk around the kitchen and nearby, and hear how in some places the hum of a fridge or microwave (or youself:) is much quieter than in others, so you can kind of plot out Chladni patterns on the volume of your home
Is a cinnamon donut bat
What about the Jam 🦇 ?
This works if the plane is high enough and not too far. Otherwise unequal spectrum ahead and back from the turbo engine comes into play.
How so? The delay is only worth of few meters for sound, about a meter for a plane. I don't see how that would make a significant difference in direct and echoed sound. Or you're saying that on approach we hear the front, on retreat we hear the back, and that is also a factor? I guess, but the moving pattern is still there, just on a different background...
@@aleksandrberdnikov2439 Yes, the front and rear sounds of a tubine are vastly different. I have been a lot on the airfield with jets and know how much the angle to the turbine matters.
Interesting. I'll try to look at spectrum of sound of low flying Jas-39 Gripen. It makes almost starwars-like sound of passing spaceship (but inconveniently loud). I guess it's combination of intake compressor/fan noise, this effect, doppler effect and simply moving at 700km/h at 200m altitude or so. But interestingly L-159 Alca which uses the same training corridor sounds different.
10/10 very good video!
I've been listening to planes since watching this video for a couple weeks, and I seem to only hear pitch going down, not coming back up. Any thoughts? I live surrounded by grass & forest - I'm guessing they have poor reflectivity...
That's a suggestion I've heard here a few times. I've been mostly dismissing it saying that I hear it well on loans, in fields, in the trees, but after your comment I tried to check if a more dense meadow/bushes would make a difference, but couldn't (had no luck catching the occasion). Still, I think some other factors might be more important here. 1) Because of stuff similar to the Doppler, more acoustic energy is emitted forwards than backwards, so the climb of the pitch is more quiet. 2) Because the sound is only a few times faster than the plane, it lags quite a bit, so the pitch doesn't start to go up until the plane is way past overhead (and when it does, it ramps up its speed gradually, so for some time it sounds kinda stationary). Also, the closer the plane is to horizon - the more the sound can be obstructed by trees, buildings etc., and a loud background may overtake it. There's also a different thing that the pinned comment talks about. Hope that was helpful.
Love this video! Do you know if there any publications/books which discuss and study this acoustic interference effect? I'm sure there are and I just am not educated enough in this field to know where to look.
Same here. People mention here a lot "comb filtering" and "flanging", which are, apparently, the terms for this effect in literature, so if you google these key words you might find something.
@@aleksandrberdnikov2439 Thanks a bunch!
Very interesting! It may solve why when I hear jets fly near where I live sounds really weird, like you don't hear anything then suddenly you hear a rapid descending white noise, then normal plane flying noise, then the pitch rises sharply and is then cut off.
Thanks! This was an amazing description of the phenomena and the cause. Please make lots more videos!
physics boys
interestingly enough there's a guitar effect that is called flanging that is often said to sound like an airplane and it works with a similar logic: adding a very slightly delayed version of the signal to the signal itself while slowly changing the delay time. nice.
interestingly enough there's a guitar effect that is called flanging that is often said to sound like an airplane and it works with a similar logic: adding a very slightly delayed version of the signal to the signal itself. nice.
Wow! This is so interesting
GENIUS!
Wow. Really excellent. This should be an intro to audio recording. Miking and mixing are almost perfect extensions from here.
no mention of the dead flash game site from 10 years ago?
did i just witness a 4 dimensional explanation?
It’s always crazy to me how common comb filtering really is in the real world, it’s so often used as an extreme effect in produced music but is really just nature at work.
Awesome work, I understood both things (doppler and echo) in a practical and entertaining way.
I suppose that the "single frequency" sound at 8:00 is from the actual engines, spinning at that freq (or half, quarter, ...)
I thought so to, but I think the explanation in the pinned comment makes more sense.
@@aleksandrberdnikov2439 interesting, i didn't notice that
I just experienced a puzzling pitch shift from an AC unit (as I walked past) and CZcams recommended this video.
A way to develop techno-paranoia :)
EXCELLENT - thank you. Always wondered why the frequency goes up as plane goes away.
I've had many planes fly over my head, and never has the pitch risen after the plane flew over. It also never changed when I changed position relative to the ground.
I've wondered about this for so long! It's one of those things that just get shrugged off if you bring it up in a conversation, so I never made the connection. I did see an application for it, a flashlight for the blind. By having a handheld white noise generator that emits in one direction, you could reveal portions of a whole room. Tested it a bit myself, even though I have no training in echolocation I could easily get around a pitch black room and tell if something was there and how far, even the density of it, like cloth vs metal, and it worked better than clicking since it gave you a constant awareness. With a bit of practice, we were able to play catch in a totally dark room, granted the ball had to be something like a beach ball to reflect enough sound
Is there something with this "acoustic lantern" that I can google? I knew about the clicking trick, but what you describe seems much more noob-friendly) Will try with a phone I guess...
omg, great video
Can you explain what parameters you used for the spectrogram? I'm having trouble getting the one I've written to look that clean. Yours seems to have excellent resolution both in time and frequency. Thanks, great video! It's inspired me to play around with comb filters, trying to replicate the effect.
I think I used Hann window (1+cos) and also tuned down a bit higher frequencies in the intensity plot sometimes, so that it looked more neat. The exact numbers I couldn't tell, I just fiddled with them until the result was clear enough.
@@aleksandrberdnikov2439 you don't remember what the FFT size or zero padding was? The main thing that I'm having trouble with is getting time resolution as good as yours, and I can't figure out if I need to have a smaller hop interval or something. Thanks for the info anyways, I'll keep playing with it. What did you use to make this spectrogram?
@@theDemong0d Well, it varied case to case I think; at least one set seems to be "samples of length 500 from 8Khz file taken each 1/240 of a second with no padding and Hann filter"; I think I did some padding for the voice bit, but it's not saved anywhere, so I can only advise to pick some setting and tune it towards the desired outcome. For everything - graphics-wise - I've used Mathematica; I think it's really not an optimal tool for it, it's just the one I'm familiar enough with to not have to deal with the coding learning on top of everything else.
@@aleksandrberdnikov2439 sounds good, thanks anyway. I should probably write some more robust interactive controls so I can tune it on the fly more easily
incredible video, never would've thought it was just reflected sound
Helicopter flew over my appartment right at the end of this video, good thing i was inside, i would have looked like a fool if i was outside rn.
0:00 sounds kinda like a phaser
Great video!
Sounds like the flange effect on guitars. I’m sure it’s produced using sine wave interference in a circuit. Awesome.
Some of the effect may be due to change in the levels of air density the sound moves through.
the Berdnikov effect
can i say that this is similar to the thin film interference on bubbles or something? but just with sound and different colors are different pitches?
There are definitely some parallels there, sure. The film is more like 2 different echoes maybe, but overall - yeah.
Great graphical representations man. Well done. Subbed.
Omfg I've been looking for what this phenomenon is and this video finally answered it! I could recreate it with a comb filter/phaser but I never knew why this happens in real life :D
It was just insane to understand)
this is awesome wow