What Does Acoustic Interference Look Like?

We use the strobing schlieren effect to visualize acoustic interference between two 28 kHz sound waves. Recognizing where constructive interference must take place allows us to interpret bright bands of light that appear in the continuously illuminated schlieren image.
Special thanks to Dr. A. Klales, who first suggested we try this experiment, and also thanks to J. Peidle, for showing us how to externally trigger the strobing LED!

Пікірлер: 98

  • @zakolia
    @zakolia4 жыл бұрын

    Shlieren effect and standing waves is a super fascinating mix. I would really enjoy playing with the possibilities.

  • @Zeno2Day
    @Zeno2Day3 жыл бұрын

    Excellent demonstration

  • @GlutesEnjoyer
    @GlutesEnjoyer4 жыл бұрын

    amazing demonstration. thank you!

  • @shawnphillips4804
    @shawnphillips4804 Жыл бұрын

    Absolutely amazing!

  • @davidnikon8501
    @davidnikon85013 жыл бұрын

    I love learning from you.

  • @treyharper7885
    @treyharper78854 жыл бұрын

    Wow, so fascinating! Thank you very much, you're an excellent teacher.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    thank you

  • @choppps5858
    @choppps58583 жыл бұрын

    Looks like real magic. Totally impressive

  • @MrEstebanEscudero
    @MrEstebanEscudero4 жыл бұрын

    Great video!

  • @maitland1007
    @maitland10074 жыл бұрын

    Pretty nice mirror you have! Thanks for the video.

  • @backonrun626
    @backonrun626 Жыл бұрын

    Wow this was very educative

  • @nickplaysviola
    @nickplaysviola3 жыл бұрын

    this is so good, thank you

  • @patiram5439
    @patiram54393 жыл бұрын

    Nice project

  • @bookdream
    @bookdream4 жыл бұрын

    This is fascinating and beautiful, I want to see more sound waves and fluid dynamics with this imaging technique.

  • @IronMoe
    @IronMoe2 жыл бұрын

    this is very nice

  • @shamsulalamdhaka
    @shamsulalamdhaka4 жыл бұрын

    Nice. Thanks.

  • @adrianskotniczny5413
    @adrianskotniczny54133 жыл бұрын

    nice job

  • @funnycatvideos5490
    @funnycatvideos54902 жыл бұрын

    Light looks exactly like this when I leave my light on, through a slit in my bedroom door. Awesome that could definitely explain the double slit, just pressure mediations in the medium, nothing is being emitted lol.

  • @il_vero_saspacifico6141
    @il_vero_saspacifico61413 жыл бұрын

    Soooo cooolll

  • @xxcood
    @xxcood3 жыл бұрын

    Hi there, it waz very interested to see some with a real knowledge about an idea that came to me since 10 years, and i wonder if you get with your knowledge to the results i did, but i couldn't deploy it because i was not my bath and also i didn't have the resources, you did mention about the levitation an opject with a sound wave, did you ever consider for levitation the source of the sound with those waves?

  • @kguy152000
    @kguy1520004 жыл бұрын

    Wow

  • @hawkfpv1636
    @hawkfpv16363 жыл бұрын

    Reminds me of the double slit experiment

  • @cheyennealvis7899

    @cheyennealvis7899

    3 жыл бұрын

    yup. follow that line of thought and you'll come to an amazing realization. But if you tell people they'll laugh at you. So it's better to just give them the bread crumbs they need to help them figure it out themselves.

  • @ed-xs3pu

    @ed-xs3pu

    3 жыл бұрын

    That light is only a wave and the particle theory was to cover up the fact that they couldn't admit they were wrong?

  • @smokysmoka
    @smokysmoka2 жыл бұрын

    💙

  • @realamerican6161
    @realamerican61614 жыл бұрын

    Wonderful experiments.. I would like to see the two emitting sources placed into one-another. Placed in such a manner that the position of the 2nd emitter may be adjusted spatially so the node/anti-node can coincide with the 1st. Much the same as you did with the glass plate. I enjoy the videos Wolfgang...

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    Thank you. We'll try aiming them at each other some time in the near future.

  • @ScientificSolutions
    @ScientificSolutions4 жыл бұрын

    Very nice, thank you for sharing this new video! What I would like to know is, from one of your earlier videos in which you suspend balls on the standing waves, are you able to feel (with your finger, or a wand of sorts, etc) the compression zone boundaries?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    No, I don't feel a thing with my finger.

  • @zakolia

    @zakolia

    4 жыл бұрын

    Wolfgang Rueckner hmm.. maybe you should see a medicine doctor!?

  • @zakolia

    @zakolia

    4 жыл бұрын

    That's a question I had in mind for a long time, thanks.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    @@zakolia I believe most human body senses require a stimulus of the order of at least 1 millisecond long, or longer. 28 kHz has a period of 37 microseconds.

  • @zakolia

    @zakolia

    4 жыл бұрын

    Wolfgang Rueckner wow! That's a great answer, thanks a lot. But I meant that as a joke: don't feel A thing with your finger... Thanks for your professionalism.

  • @shaunlewia9710
    @shaunlewia97103 жыл бұрын

    has a variation been tried with the double split experiment, to me it seems the wave forms are partictice when one transducer observes the other, and by the end we see everything is a wave. just time and case for observer for items to become solid. Blown my mind

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    3 жыл бұрын

    Unhappily, our mirror is not large enough to do a double slit type experiment.

  • @ed-xs3pu

    @ed-xs3pu

    3 жыл бұрын

    The double slit experiment is the lightwave version of this. It has been falsely claimed to prove light is a particle, but we see quite obviously that it's just wave interference.

  • @AbeDillon
    @AbeDillon4 жыл бұрын

    If you offset the frequency of one of the transducers by 30-60 hz would the camera pick up the beat frequency?

  • @NatSciDemos

    @NatSciDemos

    4 жыл бұрын

    In principle it could be done, but as a practical matter it would be complicated by the fact that these particular transducers do not give a constant power output for all frequencies.

  • @ccc321321321
    @ccc321321321 Жыл бұрын

    Hello, professor, the video uses this method to see the movement behavior of waves in the air. Is there a way to see the movement behavior of the transducer?

  • @NatSciDemos

    @NatSciDemos

    Жыл бұрын

    The transducer moves under the influence of a sinusoidal current, just like a transducer in, say, a stereo speaker. Because it's driven near resonance, the phase between the motion and input current will differ by about 90 degrees. Viewing the motion visually could be done using a very fast (approx 28 kHz) strobe light, but it would still be difficult to see because of the small amplitude.

  • @MrJdcirbo
    @MrJdcirbo4 жыл бұрын

    You didn't talk about destructive interference, where crests meet troughs. That's part of the interference pattern. Otherwise, awesome video! I love how the strobe frequency created the illusion of a standing wave. Brilliant!

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    thank you

  • @mark5150ty
    @mark5150ty3 жыл бұрын

    Has anybody tried using infrasound with this setup?

  • @karlharvymarx2650
    @karlharvymarx26503 жыл бұрын

    The sound is ultrasonic, so by definition I can't hear it and even if I could, the audio is low pass filtered at about 15.5kHz. Yet I can hear something when the emitters are running. To verify that I'm not hallucinating, I downloaded the audio and had a look at the FFT. They really do seem to be producing extra sound, strongest at roughly 14.25kHz and 14.6kHz. I have noticed the same thing using cheap piezo buzzers to play with ultrasound at home. Is it caused by alternate vibration modes in the emitters, rattling, or something else? It is loudest at the et the end of the video.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    3 жыл бұрын

    The transducers are known to also emit sub-harmonics

  • @indiarajasthan4707
    @indiarajasthan47074 жыл бұрын

    Yahooo

  • @WakarimasenKa
    @WakarimasenKa4 жыл бұрын

    The troughs interacting with each other would also be constuctive intereference, right?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    correct

  • @WakarimasenKa

    @WakarimasenKa

    4 жыл бұрын

    @@wolfgangrueckner7151 thanks

  • @zakolia
    @zakolia4 жыл бұрын

    Can you show gradually decreasing sound frequencies with corresponding strobe frequency? We could see the waves stretch appart.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    I'm afraid we can't do that with our transducer because it's a fixed frequency. Otherwise, it would be possible.

  • @zakolia

    @zakolia

    4 жыл бұрын

    Ok, thanks for answering. I really like your videos

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    @@zakolia thank you

  • @zakolia

    @zakolia

    4 жыл бұрын

    @@wolfgangrueckner7151 I mean, we could tell if the sound waves are quantized. Streching them apart hertz by hertz and see if it jumps straight to the next position. I would love to play with your contraptions!

  • @axelvf1981
    @axelvf19814 жыл бұрын

    Great video! I'm working on a project where we are looking for someone to visualize three different acoustic frequencies with schlieren photography. Would you be able to help us? We would of course be able to reimburse for your work.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    I would need to know more details (concerning what you want to do and see) to know if I can help you.

  • @axelvf1981

    @axelvf1981

    4 жыл бұрын

    Of course! Can i send you an email?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    @@axelvf1981 Certainly. It's ruecknerw@gmail.com

  • @johannesdeboeck

    @johannesdeboeck

    3 ай бұрын

    This sounds very interesting. Did you manage to do this?

  • @tristang444
    @tristang4444 жыл бұрын

    Could you rotate the pair of transducers so we could see it three dimensionally?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    In principle, that could be done. In practice, that would be extremely difficult with our present set-up.

  • @websonic1000
    @websonic10003 жыл бұрын

    HI, It would be great if you would oblige us to do experiment with double slit experiment with your setup.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    3 жыл бұрын

    We need a larger mirror to do that ...

  • @websonic1000

    @websonic1000

    3 жыл бұрын

    @@wolfgangrueckner7151 Pitty, Have this feeling that Schlieren effect could show us what is happening with light beam before entering one of those two holes and after.

  • @vladmatsala9753
    @vladmatsala97533 жыл бұрын

    How does that mirror work? Is that some camera mode?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    3 жыл бұрын

    It's a concave 2-m focal-length telescope mirror

  • @geoffrygifari4179
    @geoffrygifari41794 жыл бұрын

    i think its remarkable that transducers shoot up sound waves that go somewhat in a straight beam instead of diffracting outwards

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    It's because the transducers a flat and not a point source. The waves do diverge because the flat areas are not all that large.

  • @geoffrygifari4179

    @geoffrygifari4179

    4 жыл бұрын

    @@wolfgangrueckner7151 for how long do you think the waves would not diverge? several meters?

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    @@geoffrygifari4179 Generally speaking, waves diverge from their source by the ratio of their wavelength to the diameter of the source. In our case the wavelength is 12 mm and the transducer diameter is 45 mm. Thus, 12/45 = 0.27 radians, or about 15 degrees. And that's pretty much what we see in the video.

  • @rogershanklin3210
    @rogershanklin32103 жыл бұрын

    Why can we see the constructive interference, but not the actual, or whole(?), wave?

  • @NatSciDemos

    @NatSciDemos

    3 жыл бұрын

    To see the constructive interference, we use continuous illumination. We don't see the traveling waves under continuous illumination because they move very fast (the speed of sound is about 340 m/s).

  • @AbeDillon
    @AbeDillon4 жыл бұрын

    Why does ultrasonic sound travel so linearly?

  • @NatSciDemos

    @NatSciDemos

    4 жыл бұрын

    The waves are seen to spread out only a little bit in the picture because the transducers are flat surfaces and we're looking at a very close area around them. In other words, if the transducers were more like point sources then we would see the waves radiate out at a wider angle.

  • @AbeDillon

    @AbeDillon

    4 жыл бұрын

    @@NatSciDemos That makes a lot of sense. I've heard that higher-frequency sounds travel more linearly than radially, but it makes much more sense for that to be a consequence of the transducer than an inherent property of high-frequency waves.

  • @fattmouth7715
    @fattmouth77153 жыл бұрын

    Love it. Problem is the guy's voice puts me to sleep.

  • @deilusi
    @deilusi3 жыл бұрын

    rotate it 90' and add those tiny balls for extra effect.

  • @primodernious
    @primodernious3 жыл бұрын

    in theory you chould be able to levitate a small object with only two transducers in this configuration.

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    3 жыл бұрын

    correct ... and many people do it that way

  • @patiram5439
    @patiram54393 жыл бұрын

    Easily found slowly bites 2.8 2.8 2.8 speed

  • @j3ckl3r
    @j3ckl3r3 жыл бұрын

    I want to see what happens when you try to levitate a ball in it

  • @patiram5439
    @patiram54393 жыл бұрын

    Nies

  • @vanotank1645
    @vanotank16454 жыл бұрын

    даёшь такой опыт на 2 щелях

  • @cheyennealvis7899
    @cheyennealvis78993 жыл бұрын

    he solved the problem relating to quantum mechanics and the double slit experiment and the nature of particle vs wave without even knowing it lol.

  • @SuperDatsun71
    @SuperDatsun713 жыл бұрын

    Nikola tesla said this if I'm not mistaken already

  • @labbeaj
    @labbeaj2 жыл бұрын

    Looks like the clouds above our heads.... Especially, if the Nexrad Radars actually are manipulating the clouds instead of predicting them.

  • @GTAVBM
    @GTAVBM3 жыл бұрын

    This explains how ancient megaliths were moved around in the past.

  • @GPCTM
    @GPCTM2 жыл бұрын

    1:45 really?! an Harvard man stating the obvious? omg it's "simply because" the light travels at different speed in that region "simply because" the density there is different "simply because" the pressure is different and because of that temperature is different and density affects light speed...

  • @fvfdbsj
    @fvfdbsj3 жыл бұрын

    after 3:33 this starts to giving me headaches this sound is so annoying

  • @tameraiead5212
    @tameraiead52123 жыл бұрын

    Looks fake but sounds true

  • @lalitpal9302
    @lalitpal93024 жыл бұрын

    The sound/vibration of AUM is very important in Hinduism. In yoga the there is whole science behind sound/vibration. The whole universe is menifested in vibration/sound which is AUM as per Hinduism. AUM is base of all sound just like red, green and blue is the primary color in the world of colors . I wish modern scientists can explore more into vibration/sound.

  • @tamaseduard5145
    @tamaseduard51454 жыл бұрын

    Thank you sir 👍🙏 I remain to my idea that the formula of energy is this: ENERGY = ( ETHER / MATTER ) X ( RATE OF CHANGE )

  • @chadcarvell1908
    @chadcarvell19084 жыл бұрын

    Not at all like a double slit experiment.... Wink wink

  • @wolfgangrueckner7151

    @wolfgangrueckner7151

    4 жыл бұрын

    Correct. The waves radiate outward from the slits whereas these are planar waves.

  • @nicolascovers.
    @nicolascovers. Жыл бұрын

    goofy ahh ohio physicist