Acoustic interference (flying over our heads)

2022 ж. 25 Қар.
55 985 Рет қаралды

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  • The sound at 8:00 that demonstrates the Doppler effect isn't from the plane's engines -- it's the same effect as blowing across the top of a bottle and making a sound. It only happens at low altitudes because it's speed dependent and jets of that size at low altitudes are moving slowly because they're either just taking off or about to land. On the Airbus A320 series of planes, it's the holes in the wing that allow air into and out of the fuel tanks as the outside air pressure changes, and the sound can be lessened by disrupting the air flow over the opening. kzworld.info/throw/bejne/gXqgbdeLmHquqoM

    David LynchDavid LynchАй бұрын
    • damn thats so cool, thanks for sharing. Also Alek amazing video!

      v44nv44nАй бұрын
  • I can't wait for the next plane to fly over so I can do the squats!

    Fred OverflowFred Overflow3 ай бұрын
    • @Aleksandr Berdnikov amazing, thanks for the amazing video!

      v44nv44nАй бұрын
    • @v44n You can do that and hear a change, but it's much less clear than with a solid wall or floor.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
    • @Aleksandr Berdnikov i am curious if you do the same but with your hand to any sound. Depending on which direction are facing you hand with you ear

      v44nv44nАй бұрын
    • Jets everywhere here... Definitely gonna check this out

      Mad ScientificMad ScientificАй бұрын
    • I produced the "shshshshshsh" white noise with my mouth and went closer and farther to the wall 😂

      potatopotatoАй бұрын
  • This is a great video! I would totally have answered "the doppler effect duh" if asked about this phenomenon before

    Dr. Trefor BazettDr. Trefor Bazett3 ай бұрын
    • So would've I, for the most of my life:)

      Aleksandr BerdnikovAleksandr Berdnikov3 ай бұрын
  • The spectrogram at 8:09 is SO COOL! Also casually discovering this phenomenon in your daily life rather than is just a massive flex. Well done and congrats on following your curiosity to investigate this! This is a very well produced video, I'm very glad I clicked on this. The broadband noise might be due to mixing of air turbulence behind the aircraft en.wikipedia.org/wiki/Jet_noise while the tone that you can hear/see a Doppler effect of might match the engine RPM (I would be surprised if it doesn't, and would love to know what else might it be.)

    Ocean WongOcean Wong3 ай бұрын
    • I would expect it to be the number of fan blades multiplied by the revolution frequency, since each blade should produce at least one peak and trough. There would probably be harmonics, and a lot of interference with waves from adjacent blades

      Number1Number1Ай бұрын
  • Damn I love this video. My high school was right under the take-off route of a nearby airport, and I finally know why the sound of planes flyinng over would change when we switched seats in the classroom! A question that has been haunting me for more than a decade finally got answered!

    ExplodingONCExplodingONCАй бұрын
    • Same! Although not a decade.

      RigoRigoАй бұрын
    • That's really cool that you've noticed it for a puzzle that it is! Making this video let me realize how many more situations I've witnessed this effect in (like the one you described, say), yet it never occurred to me to see there a question in need of an answer. On the other hand, it became a bit annoying taking a note of it every damn time, can't unhear it now:D

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • The doppler-effect that you're hearing is from a the howl of the the turbine or compressor, which is a constant tone, rather than the nearly white noise of the efflux coming out the rear of the engine. The white noise gets the delay "resonance", because it is composed of nearly every frequency, while the howl is hardly affected, because it's a pure tone.

    John DoeJohn DoeАй бұрын
    • @John Doe ah - I misread you

      FlyNAAFlyNAAАй бұрын
    • @FlyNAA which is why I mentioned both. Depending on the engine design, the majority of the howl can come from either one.

      John DoeJohn DoeАй бұрын
    • I wouldn't be Kramer-ing in to random internet discussions with this, but since we're picking apart geeky details... the front part is called the compressor, or fan, but not turbine. That's the part in the back.

      FlyNAAFlyNAAАй бұрын
  • I used to sit on a rocking chair near a river and every time the rocking would create this going up and down of the frequency. I toyed with it and got the feeling this was weird, because the sound didn't revert to normal when I stopped moving, it depended on my position. Now I understand why. Thanks!

    Germain DeslogesGermain DeslogesАй бұрын
    • pretty safe to assume your rocking chair was next to a wall, and the wall was creating the reflection?

      diggorandiggoranАй бұрын
  • Aka comb filter. very well made video on this topic. Haven't heard anyone talk about the evennes and oddnes of it. You can then think about this phenomena with regards to waveforms, Sawtooth and squarewave then become quite interesting.

    realityassemblyrealityassemblyАй бұрын
  • 5:15 An experiment that anyone following can do is to blow at finger keeping it in front of face and listen to the reflected noise - it changes in corelation to distance, not to the velocity of the finger. Regarding overall topic of the video: very cool observation and clever explanation! I was intrigued by 3Blue1Brown video regarding SoME2, but not spoiled with the explanation - tried to think about it by myself and did not figure it out :)

    kabotteamkabotteamАй бұрын
    • that's probably more because the velocity of the air changes with the inverse square law

      Waffles SyrupWaffles SyrupАй бұрын
  • The quality of this video is on par with many much bigger channels, and it teaches a thing I had no idea about despite having been watching sci-pop for years. The graphical aspect is superb, exactly what is needed to explain such a complex topic. Amazing job!

    Dmitrii DiveDmitrii DiveАй бұрын
  • I've been baffled by this effect for the past 20 years of my life. Amazing to run across this excellent explanation by random chance today!

    knurlgnar24knurlgnar24Ай бұрын
  • 8:00 i can hear both phenomena there! Wow that's awesome! Thank you sir for this video.

    Michael HanfordMichael HanfordАй бұрын
  • Really interesting! I have always thought Doppler as well. in music production /sound design this effect is called comb filtering.

    Liam QuinnLiam QuinnАй бұрын
  • Sometimes you can hear the sound of a plane start very abruptly. Often so that different frequency components of the sound start at a slightly different time. I've been wondering about what causes that. I've been guessing at some type of total internal reflection type thing occurring between air layers obscuring the sound initially, and then suddenly allowing the sound to pass when the geometry changes as the plane moves. If you know something of this, I'd love to hear about it :-)

    Antti HuhtalaAntti HuhtalaАй бұрын
    • ​@Antti Huhtala Yes. Thats what I have in mind. As a child, not knowing many about turbine engines, I guessed the plane was something like "putting the brakes on" aproaching the nearby airport.😆 ​ @Antti Huhtala Yes. Thats what I have in mind. As a child, not knowing many about turbine engines, I guessed the plane was something like "putting the brakes on" aproaching the nearby airport.😆 ​ @Antti Huhtala Yes. Thats what I have in mind. As a child, not knowing many about turbine engines, I guessed the plane was something like "putting the brakes on" aproaching the nearby airport.😆 ​ @Antti Huhtala Yes. Thats what I have in mind. As a child, not knowing many about turbine engines, I guessed the plane was something like "putting the brakes on" aproaching the nearby airport.😆 ​ @Antti Huhtala Yes. Thats what I have in mind. As a child, not knowing many about turbine engines, I guessed the plane was something like "putting the brakes on" aproaching the nearby airport.😆

      Comp FoxComp FoxАй бұрын
    • @Comp Fox I'm not sure if that's what I mean 😀. What I'm talking about is when the sound of a plane is first barely audible, but suddenly becomes louder. If I recall correctly, the sound starts from the high frequency end, and extends toward the lower frequencies. This takes about a second.

      Antti HuhtalaAntti HuhtalaАй бұрын
    • Do you mean the "miiiiuuuuu" sound, when a plane is approaching ? I'm wondering abouth this for a long time too. I think some aspect is the planes velocity in relation to the speed of its sound. When the plane travels faster than sound, this noise gets compressed to a supersonic "boom".

      Comp FoxComp FoxАй бұрын
  • I've been wondering about this for years after moving to a house under a popular high-altitude flight path; this video was so well done explaining the phenomenon while also fostering an interest in science. Thank you very much for making this!

    Kurt LoetherKurt LoetherАй бұрын
  • Awesome video, the recap at the end feels especially good, you are a good teacher 🙌

    György SzentgáliGyörgy SzentgáliАй бұрын
  • This assumes you are on a hard flat surface. Standing in a tall hay field is likely to drop the amplitude of the reflection substantially and allow the doppler effect to dominate.

    MyTechMyTechАй бұрын
  • incredible video, never would've thought it was just reflected sound

    its me alecits me alecАй бұрын
  • 🎉 I figured this out when I was a kid - took a while but I got the same answer. There is another effect which is equally baffling to start with related to a slatted fence by a road - when a car goes by it can produce a tone due to multiple reflections from each slat - all good fun for the whole family.

    Daveo ZipDaveo ZipАй бұрын
  • 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

    Weylin StoeppelmannWeylin StoeppelmannАй бұрын
    • 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...

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • Great video! I always thought it was the Doppler effect. Could the sound also be bouncing off the clouds if the plane is flying under a heavy overcast?

    K CameraK CameraАй бұрын
  • Sounds like the flange effect on guitars. I’m sure it’s produced using sine wave interference in a circuit. Awesome.

    silver & noisesilver & noiseАй бұрын
  • Thanks! This was an amazing description of the phenomena and the cause. Please make lots more videos!

    zenith parseczenith parsecАй бұрын
  • The gradients of temperature and pressure change the speed of sound by altitude, and the sound waves are bent toward the side of lower speed. One result is that it's hard to hear the noise of an airplane on the ground from a distance away, but the loudness increases sharply as the plane takes off.

    Peter VanderwaartPeter VanderwaartАй бұрын
  • Awesome work, I understood both things (doppler and echo) in a practical and entertaining way.

    OsoreruOsoreruАй бұрын
  • 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.

    GoogahgeeGoogahgeeАй бұрын
  • I was searching an explanation about plane sounds for months, thanks for making this video!, learned a lot.

    Raico68Raico68Ай бұрын
  • Nice, really good explanation of something not often thought of.

    T GT GАй бұрын
  • Very good explanation and presentation of a phenomenon we’ve all experienced but probably never thought about why it appears this way.

    techdoc99techdoc99Ай бұрын
  • With regard to the distinguishable sounds that do show the doppler effect: jet engines produce sounds with specific pitches from their rotating components - the compressor, fan, and turbine. It is particularly noticeable with low-bypass engines, now only found on high-performance military aircraft, together with a few '60s and '70s airliners and business jets (in those places where they are allowed.) Specific pitches can also be generated by the airflow over the airplane, and particularly when slotted flaps are deployed. Perhaps this accounts for your perception that it is most noticeable with lower-flying aircraft, as the flaps are deployed for takeoff and landing? Another possible explanation lies in the fact that high-pitched sounds are attenuated more strongly than lower ones. This would only hold up if, when listening to a high-flying airplane, almost all of the sound one hears is lower in pitch than the distinct sounds that show the doppler effect. This is an excellent video - science exposition as it should be done, with observation, hypothesis and verification following one from the other in the right order!

    A RaybouldA RaybouldАй бұрын
  • 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.

    Pavel PeřinaPavel Peřina10 күн бұрын
  • 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.

    ChayDChayDАй бұрын
  • Great observation and amazing explanation ! Looking forward for more videos by you.

    Veyron DarrenVeyron DarrenАй бұрын
  • This concept is so cool. Thank you so much for opening my eyes for this. I do however still have a problem grasping why the different interference condition not only cancels or enhances included frequencies but also changes the pitch .. could someone maybe bring some light into that? I'd really appreciate it!

    Florian BontkeFlorian BontkeАй бұрын
    • The conditions affect the delay of the echo, and that determines which frequencies would be cancelled and which amplified. Each frequency doesn't move anywhere (disregarding Doppler), what moves is this comb pattern of cancellation/amplification. The result resembles a particular sound (with wavy spectrum) changing its pitch, so that's how we hear it.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • EXCELLENT - thank you. Always wondered why the frequency goes up as plane goes away.

    Colin RatcliffeColin RatcliffeАй бұрын
  • This is great information! What I had noticed is that I don’t hear a plane coming until it’s a certain “height” away from me, and I found that strange that it’s not a gradual increase starting as soon as it’s above the horizon. I’m sure there something related here, in that the echo doesn’t happen at low angles.

    Jerry ChappellJerry ChappellАй бұрын
  • Subbed. Great video, I always noticed this but never bothered to know the why. Thanks for making this video.

    JoyphobicJoyphobicАй бұрын
  • Some of the effect may be due to change in the levels of air density the sound moves through.

    Noah SpurrierNoah SpurrierАй бұрын
  • You’ve just explained the barber pole filtering / phasing effect well known by musicians and well described by mathematicians. Yes, it’s based on variable length delay and mixing direct signal with delayed.

    rpoccrpoccАй бұрын
  • Super interesting and incredible production value!

    epmtunesepmtunesАй бұрын
  • The Doppler effect is still there. But as you're analysing not a tone but white noise with equal frequency distribution it does not matter. Frequency shifting of white noise is still white noise.

    rkalle66rkalle66Ай бұрын
  • Very interesting, it's not unlike 'sample delay' used in audio engineering - and in fact this gives me some ideas to manipulate it in some interesting ways. Thanks!

    Harmonic Resonance ProjectHarmonic Resonance ProjectАй бұрын
  • Wow. Really excellent. This should be an intro to audio recording. Miking and mixing are almost perfect extensions from here.

    じょいすじょんじょいすじょんАй бұрын
  • The law of resonance could help us safer operations....thank you for this side way presentation...I was really nonverbal learner until now

    Tri PhamTri PhamАй бұрын
  • This question caught me some days ago when I was standing on my terrace and a plane went by above me. I thought, "If this is the good old doppler effect, than why is the pitch increasing as the plane is going past me?" I didn't put much effort into actually thinking about it but you did it for me. Thanks alot for this well put and intuitive explanation.

    ShawakShawakАй бұрын
  • There is another weird sound effect I hear sometimes. If a plane is coming in for landing approach, you will sometimes hear this weird downward drop in frequency over one to two seconds. I thought maybe it was the engines throttling down suddenly but now I'm not so sure..

    Zachrey HelmbergerZachrey HelmbergerАй бұрын
  • Hi, great video. What application did you use to create the spectrogram? Thanks

    Dave RailDave RailАй бұрын
  • To anyone who has spent time with guitar pedals or synthesizers, it's clearly the phenomenon described as Flanging. Which is very different from the dopler effect which is solely concerned with a pitch shifting, not with interference patterns like this.

    seedmoleseedmoleАй бұрын
  • awesome video, I loved the editing and explanation

    LfzinhoLfzinhoАй бұрын
  • Outstanding description of this fascinating effect. Thank you!

    Mark BeardMark BeardАй бұрын
  • 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.

    Mihály PonyiczkiMihály PonyiczkiАй бұрын
  • 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.

    MymokolMymokolАй бұрын
  • There is also the differences between the frequencies emitted by the front of the reactors and the back of the reactors. This is most distinctive with war planes flying with afterburners engage.

    The0ldg0atThe0ldg0atАй бұрын
  • 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.

    Mihály PonyiczkiMihály PonyiczkiАй бұрын
  • Thanks for creating and sharing this great video. This is one of the most interesting things I've learned recently.

    Christopher MadsenChristopher MadsenАй бұрын
  • Such a fantastic explanation!

    NonBinary StarNonBinary StarАй бұрын
  • Amazing explanation! You deserve more subs.

    Josh CampbellJosh CampbellАй бұрын
  • 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

    Xenro66Xenro66Ай бұрын
  • Great graphical representations man. Well done. Subbed.

    Geodesic InterpolationGeodesic InterpolationАй бұрын
  • Great explanation, learned something new

    Hans ElbersHans ElbersАй бұрын
  • Excellent explanation and illustration!

    mjearsmjearsАй бұрын
  • The sound of distant thunder also produces the effect of pitch dropping. First you hear high frequencies and the pitch drops as the volume increases. I've thought about that quite a bit and have no explanation.

    Jesse ParkerJesse ParkerАй бұрын
  • Thank you, this was refreshingly interesting.

    Ed PuckettEd PuckettАй бұрын
  • Great video, and great explanation!

    Bong OrdanezaBong OrdanezaАй бұрын
  • Brilliant. Loved every second.

    ody vinty*ody vinty*Ай бұрын
  • This feels like a 2blue1brown vid Keep up the good work!

    Gab GGGab GGАй бұрын
    • 2girls1brown

      Слава Україні!Слава Україні!Ай бұрын
  • Very nice explanation. Great video!

    Louis CallensLouis CallensАй бұрын
  • 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...

    Grant LarsenGrant Larsen28 күн бұрын
    • 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.

      Aleksandr BerdnikovAleksandr Berdnikov11 күн бұрын
  • Very interesting video, never thought about this before.. thanks =)

    KerzenmacherKerzenmacherАй бұрын
  • Oh no. I would have thought it's Doppler, too. This experiment proves I need to be a bit more sceptical about the world sometimes

    Beats basteln :3Beats basteln :3Ай бұрын
  • Beautiful animations!

    Scott SimonScott SimonАй бұрын
  • So it sort of creates the same sound illusion as the "Infinitely descending tone"?

    HansLemursonHansLemursonАй бұрын
  • I had noticed that a plane's noise pitch always went down and up when I was little, so when my physics teacher told me that it was doppler effect I felt confused as it didn't explain why the pitch could go up. I once thought maybe the exaust gas from the jet turbine somehow formed a wave guide, trapping noise based on wavelength and caused this odd phenomenon. Thanks to you I finally have a proper understanding! By the way is it your own idea or is it inspired by some paper?

    Bubble SongBubble SongАй бұрын
    • I'm sure it's not my original discovery, but it is an independent one nonetheless:) Same thing also was bugging me in the back of my mind whenever I noticed it, but only recently I realized what's happening there, and thanks to SoME lucky timing it wasn't lost in vain.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • Doesn't a doppler effect play into this still though? Because, while the sound has a general pitch down feeling, the interference frequency is actually following the general trend of a doppler pitch. Also, the reason proximity matters to hear a "traditional doppler effect" is because after a certain distance you don't hear any individual frequency stand out, instead hearing a particularly attenuated whitenoise profile.

    Evelyn KellyEvelyn KellyАй бұрын
  • Absolutely brilliant video.

    SSАй бұрын
  • 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.

    FloamandphysicsFloamandphysicsАй бұрын
    • @Aleksandr Berdnikov Thanks a bunch!

      FloamandphysicsFloamandphysicsАй бұрын
    • 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.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • Very well observed!

    Koen ThKoen ThАй бұрын
  • Excellent explanation.

    Myke PriorMyke PriorАй бұрын
  • Comb filtering. Reflections from the ground interfering with the direct sound.

    Jim GriffithsJim GriffithsАй бұрын
  • Really interesting, thank you

    Mr0neShotAwayMr0neShotAwayАй бұрын
  • Неплохо. Помню на лабах по физике часто подобные качественные вопросы нужно было разобрать, чтобы сдать.

    Vladimir StarostenkovVladimir Starostenkov3 ай бұрын
    • A country that actually teaches their children math and physics. Wish the US did

      tolkienfan1972tolkienfan1972Ай бұрын
    • @Aleksandr Berdnikov одну задачку из школы помню. Существует способ измерения силы поверхностного натяжения методом отрыва кольца. Так вот, демонстрируется такая установка, измеряется поверхностное натяжение воды, которое сходится в пределах погрешности метода с табличным значением. Далее в воду помещается анод, а снаружи сосуда - катод, подается напряжение и сила поверхностного натяжения меняется. Далее следует предложение объяснить почему "у воды под действием электрического поля изменяется коэффициент поверхностного натяжения". Злая шутка кроется в чистоте эксперимента: кольцо металлическое и, будучи подвешено на металлической проволоке к прибору, является проводником погруженным в воду, в которой начинается незаметный невооруженному взгляду электролиз :) Еще вопрос вполне доступный школьнику-физику - это про "очки с дырочками", темные такие очки с непрозрачными стеклами, в которых насверлено много дырок по 1-2 мм в диаметре - просто объяснить принцип их работы. Остальное уже в универе у меня было.

      Vladimir StarostenkovVladimir Starostenkov3 ай бұрын
    • Эх, у нас в школе хоть с теорией было хорошо, практики/лаб содержательных не припомню. Интересно стало; а можете примеры привести?

      Aleksandr BerdnikovAleksandr Berdnikov3 ай бұрын
  • My hat off to you, sir. Wonderful.

    Jon TimeJon TimeАй бұрын
  • Was wondering what the wide frequency range had to do with it... 🙏🤙

    Matt MountainMatt MountainАй бұрын
    • Is that a question addressed to me? If so, I'm not sure I understood it, so you'd need to clarify...

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • So, I suppose the summary should be something akin to Forrest Gump's famous line at Jenny's gave - "Maybe it's both. Maybe both is happening at the same time" 😉 Отличное видео с Саша! Спасибо и привет из Австралии!

    Aleksander Wladyslaw BachorskiAleksander Wladyslaw BachorskiАй бұрын
  • Super! Excellent graphics as well.

    Anton NiedersteinerAnton NiedersteinerАй бұрын
  • This is what the Flanger effect does. You can hear it when you "shhh" near a wall and slowly move toward and away from it. You know that you do not change the sound you are making, but you change the distance to the wall, while your distance to the floor remains unchanged. You hear exactly the same effect when moving. If you stand still, the perceived pitch will not change.

    Erik ŽiakErik ŽiakАй бұрын
    • That's what the video says

      Thomp YTThomp YTАй бұрын
  • that's an incredible video. ngl, i'm here because of 3b1b, but that video has been in my recommended for some time, so it looks like you're on good terms with youtube gods. wish you luck and channel growth.

    swancrunchswancrunchАй бұрын
  • Wow. Nice explanation by way of illustration.

    Or you know, Cyndi CorinneOr you know, Cyndi CorinneАй бұрын
  • If you use "white" light for the double slit you will see a rainbow pattern (similar to a prism). This is actually used in scientific for spectral analysis. Search for "diffraction grating" if you are interested.

    L.L.Ай бұрын
    • I enjoy using CD this way to watch the solar spectrum. There is something mesmerizing in its pure pattern of fine lines:)

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • 10/10 very good video!

    //////27 күн бұрын
  • Fascinating, thanks!

    Andy PlaterAndy PlaterАй бұрын
  • I've always wondered about this. If it's the Doppler, you'd hear two distinct frequencies which does not happen. Here from 3B1B

    potatopotatoАй бұрын
    • No, in most cases doppler will still result in a continuous transition due to trigonometry. The exception being the case where the jet passes close enough to shave your hair, but then you still have the issue that it is not a true point source and the approaching tone would be separated from the receding tone by a large amount of general noise.

      MyTechMyTechАй бұрын
  • Very interesting explanation!

    AiratglAiratgl3 ай бұрын
  • Friend: “What are you doing?” Me: “plane’s going by.” F: “so you /have/ to do the squats when a plane’s overhead?” M: “yes and you do too! Try it, quick!” 😂

    Illectryx/server642Illectryx/server642Ай бұрын
  • This effect should be heard on a parking lot, but not on a meadow, as meadows don’t reflect sound. It works on a wall, but not a curtain.

    paul snorpaul snorАй бұрын
    • I've mostly heard this effect on meadows and fields, actually (not mush else around here), so they reflect plenty. And just tried my curtains - it also worked - but they've got quite thick fabric. A T-shirt for example didn't get off much of an echo :)

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • Please place the recording device on the ground so we can isolate the Doppler effect.

    SpaceManMatSpaceManMatАй бұрын
  • Wow it might be interesting to make app which gives info about plane using sound

    Hlib prishchepovHlib prishchepovАй бұрын
  • "No one knows for certain when it became customary to 'teabag' when planes are flying overhead. Perhaps it expresses mankind's own innate desire to be airborne. Others posit that it indicates some form of ownership, despite the obvious differences in scale and capability."

    nayhemnayhemАй бұрын
    • Ahaha, lol

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • 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.

    theDemong0dtheDemong0dАй бұрын
    • @Aleksandr Berdnikov sounds good, thanks anyway. I should probably write some more robust interactive controls so I can tune it on the fly more easily

      theDemong0dtheDemong0dАй бұрын
    • @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.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
    • @Aleksandr Berdnikov 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?

      theDemong0dtheDemong0dАй бұрын
    • 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.

      Aleksandr BerdnikovAleksandr BerdnikovАй бұрын
  • Fascinating, thanks for that! There's another plane sound effect I don't understand, do you have any idea about it? When a plane goes by, its noise usually starts quietly and grows louder while it's approaching. But I often hear a plane's noise suddenly set in at high volume, as if it had just activated its engines in an instant. Sadly I have never seen the plane in those cases (due to usually hearing it from inside the house with the window open), so I don't know at which distance it happened. I don't remember ever hearing the opposite, a plane going from loud to silent in an instant. Possibly relevant: I live some 15-20 km from an airport and the planes are going relatively low here.

    m4ilm4nm4ilm4nАй бұрын
    • @m4ilm4n as someone else said, it could be that the plane is so ( horizontally ) far away that the sound is being reflected by the warmer air closer to the surface ( the same as what happens with light in some types of mirage, for the same exact reason ), until it suddenly isn’t.

      ⃠Ай бұрын
    • @Myke Priorno, I'm too far from the airport to hear those. I'm talking about planes still in the air.

      m4ilm4nm4ilm4nАй бұрын
    • if this is on landing.....almost silence post passing if their gear is down, then sheer roaring say a minute later... you are hearing the reversers, which are ungodly loud due to the sheer amount of turbulent air they create fighting against the relative airflow. It is basically full power with the majority 70%ish of thrust directed semi forwards. It is less maintenance to use speed brakes, flaps and reversers than to always use wheel brakes and wear out tires. Also prevents overheating the brakes causing undo delays waiting for them to cool and not warp. This doesn't exist on military fighters, but any commercial prop/jet plane you will always hear it.

      Myke PriorMyke PriorАй бұрын
    • @m4ilm4n my instinct says refraction is the cause. Like a sound mirage maybe? The hot air near the ground refracts the sound from a plane upwards, so if the plane is at a low enough angle in the sky, you would sit in a sound shadow. Either the sound is refracted over your head, or it's reflected off the ground in front of you, over your head. The sudden onset of sound would then be a function of height and pressure gradient in the air. To test, try climbing a radio tower out on the plains, or finding an inversion this winter. I just moved under flight path, so maybe I can keep an ear out for it.

      GreenicegodGreenicegodАй бұрын
    • @knurlgnar24 I don't think that's it. There's no military here, and I'm too far from the airport for late go around. It's not a "throttling up" noise. It's almost like someone pressed the unmute button ;) it goes from silence to a loud, steady-frequency droning in an instant, almost as if the plane emerged from a sound-proof forcefield.

      m4ilm4nm4ilm4nАй бұрын
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