Why Blowing in Bottles Makes Sound and Helmholtz Resonance

[@hacksmith]

I never really thought about it before! Great explanation -- I'm loving the blender animations -- you're getting super professional on us!

[@RimstarOrg]

Thanks! The animations are actually a lot of fun to make.

[@ranmindyt2902]

Legend

[@RimstarOrg]

Follow-up to last week's acoustic propulsion video... Why does blowing in bottles make sound? What role did the speakers play in last week's video? What's Helmholtz resonance? Hint... It's all related.

[@MediaEinstein]

My son and I love all your videos. He's only nine and he already wants to be a Physicist. Thanks for posting these, we've had hours of fun at home in the lab. I picked up a huge flyback a few days ago and as soon as i build the driver, it's my corona a go-go.

[@RimstarOrg]

That's music to my ears. Hope you both have lots of fun together, and be safe.

[@MediaEinstein]

Haha..thanks and roger that..

[@magaz639]

Best explanation on KZbin!

[@RAJLthe13]

I have a question, in practice, like in architectural acoustics, we can use helmholtz resonator as a sound absorber in order to reduce certain frequencies sound power level of undesirable low freqs. According to physics, what is actually happening during the progress of that sound reduction? Why doesn't the sound amplify instead?

[@RimstarOrg]

+RAJLthe13 I'm no acoustics expert so I can't say for sure. As an uneducated guess, it makes sense. The sound would enter the helmholtz resonator and sound waves of the frequency that the resonator is shaped for would move back an forth within the resonator, essentially trapped, gradually diminishing in amplitude as the energy is transferred to the walls of the resonator as heat energy.

[@tiffanyhouze1886]

I believe your referring to cymatics in respects to resonance from the Ether wave propagation in accordance to light or photonic beams of such . Buildings of old times were built for specific tunings with certain materials in retrospect of masonic knowledge of foundations that resonate the building thus creating a nice energy . Our recent hidden past has all the answers if you look up cymatics fundamentals of architecture. Beautiful buildings and even stoves did have infact a nice pure etheric energy using mercury and or water basically scalar waves or orgone energy. William Reich, look him up. Quite profound man he was!

[@NPRBEST]

Very good explaination by animations.

[@EMandMORE]

wonderful as always! thank you for the awesome informations with clear explanations!

[@mousaalsaeed9410]

it's a great feeling to being able to understand these things

[@GoRepairs]

Good work on the animations, they made your explanation very clear.

[@RimstarOrg]

Thanks. I gotta admit, making the animations is a fun too.

[@Autogenification]

Thanks for this info, I'm on a bit of a quest to understand the physics of water droplets, more specifically how I can recreate the sound of a water droplet through sound and FM synthesis. The end goal is to recreate Vangelis' "Rachel's Song" piece, specifically those synthesized water droplet sounds that he has in it!

[@RimstarOrg]

Sounds like a fun project. Perhaps record some droplets with a good mic and then load it into Audacity. It can even give you frequency breakdown.

[@alvik8399]

Thanks for the explanation. Helmholtz applied to traverse flute. May be you could shed some light on what happens on a side flute(traverse flute) which is some kind of mix between open hole on both sides but at the same time has to the left of the embouchure blow hole a cavity which ends in a closed end, and I believe this volume of air acts in a way as a compressor ,resonator. Would you know how this system works or a place where I could dig deeper into the matter. Thanks in advance. Alex G

[@RimstarOrg]

Hi Alex, Sorry but I don't have any information on the resonator you're describing. Cheers, Steve

[@ne0romantic]

When I have a vessel flute in the shape of a bottle and blow across the mouth as you're doing here it produces a tone, yet, when I open a single tone hole in the flute it stops working completely. However, if I plug the mouth and open an embouchure hole somewhere along the flat, without a "neck" leading to it, it works with many holes open, a little over an octave in range by opening holes. Some xuns can play a 12th that way, though, and have a shape which is not quite like a bottle shape but does have some kind of neck leading up to the mouthpiece, just not so narrow as a bottle neck. There is another shape too, which seems to correspond to instruments with larger playing ranges, that shape is wider at the top, kind of "T" shaped which they call the "ox head", also there is a gourd shape, and I don't know if these shapes are functional or ornamental. Everything I read about vessel flutes says shape has little effect, but it's written for fipple instruments, not vessel flutes with simple embouchure holes. Also the location of the tone holes in certain shapes seems to matter. If I make a tall skinny vessel which is not so tall and skinny it becomes a tube and open one tone hole only, the higher the hole the lower the pitch, which is the opposite of what I thought would happen. Can you explain any of this or do you know of any possible resource for either of these effects?

[@RimstarOrg]

+ne0romantic I don't have an understanding past what happens with one hole in a flute type instrument. However, a quick google search for "how a flute works" turned up this wonderful page newt.phys.unsw.edu.au/jw/fluteacoustics.html and there seem to be a lot more of them. If you search on that page for the section headed "Cut-off frequencies" it talks about the different affect of holes on low frequencies vs high frequencies. Looks like the high frequencies aren't reflected by the first encountered hole. I do envy your obvious knowledge of flutes and music though. I bought a flute at a yard sale a year or two ago but haven't had the chance to learn to use it yet.

[@ne0romantic]

RimstarOrg I get all that (by get, I don't mean I can do math related to things like cut off frequencies, but they're actually really important... they're the reason why rolling in and covering more can produce a louder sound from a smaller embouchure hole on the concert flute which seems counter-intuitive; it's because the harmonic frequencies are higher and not affected as much as the fundamental so you can actually bring them into relative tune with each other by changing the embouchure.) That's not what I was asking about at all though I think vessel flutes are affected by cut off frequencies as well. For my second question by "higher" I meant higher up on the instrument, not a higher pitch. For my first question, the stopping point I'm encountering as I make more tone holes isn't the holes acting like they aren't there (from cut off frequencies) it's the sort of the opposite, like there are too many holes and there's no pressure to blow against. Thanks for the response, though; it was worth a shot.

[@ne0romantic]

I just found the answer elsewhere on that website in case anyone is curious. It's "The inertance of a hole depends on the ratio of its effective length to its cross sectional area. (I've included 'effective' because, for a quantitative answer, one must include the end effects, as explained in Helmholtz resonance.) If you drilled normal-sized tone holes in a bottle, their inertance would be much lower than that of the neck of the bottle, so the neck would be short-circuited. Ideally, then, the tone holes for a bottle-ocarina would need to have ratios of effective length to cross-sectional area that are comparable with but a bit larger than that of the neck. You might like to try this using lengths of drinking straw sealed in holes in the bottle. There may however be problems caused by losses at any sharp corners, which would reduce the quality of the resonances." From: newt.phys.unsw.edu.au/jw/musFAQ.html

[@vivianrichards3434]

"What is science?" Its the refinement of everyday things! Quite satisfied with your explanation. So, when we whistle, does it also work on the same basics?

[@RimstarOrg]

Interesting. I had to look that one up. I turns out whistling isn't based on this but it is enhanced by the mouth working as a Helmholtz resonator.

[@PhunkieZero]

Good video, always enjoy learning what makes things work like this

[@TomCoteTheTomCoteShow]

I used to be in a band called "Helmholtz Resonance"...

[@RimstarOrg]

Good name! Even now your music resonates with people very well.

[@TheSalto66]

What is amazing is also the fact that final moment is orthogonal at the direction of propagation of sound waves....like magnetic field around a wire with electric current

[@RimstarOrg]

The sound waves are themselves areas of compression and expansion. When an area of expansion gets to the hole in the bottle, it expands into the bottle. So it looks orthogonal but really, where the wave interacts with the hole it's in the same plane... which is pretty neat too.

[@Stithsonian]

Wonderful job with this! I'm working on getting it to work myself. I had a few questions if you had some time to answer: 1. The horizontal bar attached to the bottles--what affect does its length have? Longer would seem to take more force to begin moving, but minor imperfections on balance would seem less important with a longer arm. 2. Is there a reason why the speaker is below the bottles (as opposed to aimed at them)? 3. Is there any reason it would be much easier with larger volume bottles than same 12 oz? Thank you!

[@RimstarOrg]

+Douglas Stith Thanks! Re your questions: 1. Due to the "lever principle" the longer the bar is the easier it is to get moving, though the trade-off is that it will start moving more slowly. Once momentum has built up it doesn't matter anymore. 2. There's a jet of air coming out of the the bottle. You can see it my other video here kzbin.info/www/bejne/gmbJh3l3Z9iKqpY. If you were to aim the speaker directly at the bottle then it would oppose the creation of this jet inside the bottle. It wouldn't move, or have a harder time moving. 3. It's actually harder to move larger volume bottles. I've tried. That's because the Helmholtz resonant frequency for larger bottles is lower and so there is less energy resulting from it.

[@Stithsonian]

+RimstarOrg Thank you for this very helpful feedback. Again, wonderful job with this. By the way, I am driving my bottle with an iPad hooked up to a large amp. I have an app that allows me to tweak the pitch of my tone. Thanks.

[@obscurecult]

Hello. Could you explain to me why we have to blow at a certain frequency for the bottle to emit a clear sound? Otherwise it produces a the note but with a lot of noise. Also, if I blow a little harder the note rises. What are the physics of the blowing part?

[@Hamachingo]

Question: I intend to build Helmholtz Resonator Bass traps (i.e. lots of dampening material inside to "eat up" the resonant frequencies. Will putting something like a thin breathable cloth or mosquito net across the hole still make is work on lower (below 200 Hz) frequencies? I'm building big ones with drywall and don't really want bugs nesting in there.

[@RimstarOrg]

I could be wrong but I suspect that putting something over the hole won't change the frequency that it resonates at. The formula I show in the video at around 1:49 takes into account only the bottle's geometry.

[@quintonbates5281]

Thank you 🙏🏽 and what about pressure coming through the other way like from inside the bottle?

[@RimstarOrg]

I don't understand your question. Which part of the video do are you referring to?

[@quintonbates5281]

@@RimstarOrg like can you funnel sound with a plastic bottle or is it just the pressure inside is what makes the sound

[@RimstarOrg]

Sound is made up of waves. The waves are areas of low pressure air next to areas of high pressure air alternating from one to the other. So it's the constantly changing pressure inside the bottle that I show at 0:54 and the resulting sound that I show at 2:00.

[@deadlizarddead]

I wonder if it would work better if you played back a loop of the actual audio of the bottle making sound. you could probably mess around with eq and effects to make it behave differently.

[@RimstarOrg]

Benn Laidlow I played it back like you suggest in the video before this one in order to make a bottle move. You can see this in my video "How to Move Things with Sound/Acoustic Propulsion". I didn't mess around with the eq though.

[@ashutoshbhakuni303]

Great. But shouldnt the explanation also include why the oscillation produces a net thrust in one direction rather than zero thrust? I was seeing somewhere that at higher amplitude the flow changes and air is drawn in from the sides of opening while a jet flows out from the center. If so, Why does that happen?

[@MilanKarakas]

Thank you for posting this video. It is even better explanation than previous one: How to Move Things with Sound/Acoustic Propulsion Is it possible to put similar bottle on a boat (made of styrofoam), and by applying some noise (or resonant frequency) to make air-jet propulsion? At least in a bathroom. Okay, I think it will not make lot of thrust, but anyway - maybe it is worth to try. (currently I haven't any audio system that can produce very low frequencies - the loudspeakers I have on the computer is very bad one, and no way to reproduce such low frequencies with significant sound pressure. Smaller bottle, I bet it resonate at enough high frequency that may be pretty annoying to play with. Maybe amplifier onboard + loudspeaker inside the Helmholtz resonator (bottle) ? What you think?

[@RimstarOrg]

Trying it on a boat in water is a neat idea. There's not a lot of force here. I did put my hand behind the jet and definitely felt something, a little more than a gentle breeze. It might work. You definitely couldn't also carry any extra weight though, like an amplifier and loudspeaker.

[@sleepygrumpy]

Excellent video!

[@prateekyadav9811]

This was perfectly demonstrated. Thank you!

[@USWaterRockets]

Awesome! I video featuring soda bottles! We love soda bottles! LOL. But seriously, this is a great demonstration of the effect and the animations make it really clear. Another good science video!

[@RimstarOrg]

Thanks. And I hadn't thought of that! This is another way of propelling those bottles. Clearly related to your work!

[@Lidmotor]

Thanks for this very good video on resonance.

[@RimstarOrg]

Thanks. I hope in the near future to do one purely about resonance with a spring, swing, possibly this Helmholtz resonance and a parallel LC circuit as examples, or something like that.

[@bagmet7562]

Wow ! Is there any industrial use of the propulsion effect ??

[@RimstarOrg]

+Bag Met I've never looked into it. But I'm guessing some clever engineer out there has made use of the effect somewhere in some manufacturing process. Probably not for propelling anything though but just for the air flow.

[@jnhrtmn]

Then, the pop pop boat drive effect is the complication beyond that. The air going into and out of the hole should cancel out, but there is a driving result. The air going out is in a different situation than the air going in. The air going in comes from a larger source of air with less inherent momentum, but all of the air going out had to make a 180 degree turn first, so the slender ordered exit is a key feature to the drive. I doubt it would work without a neck in the exit.

[@lucasriello]

Is it possible to produce harmonics by blowing into the bottle? Like a higher octave?

[@RimstarOrg]

That, I don't know. I you blue pulses of air into the bottle at some frequency, I don't know what you happen.

[@lucasriello]

@@RimstarOrg i'm trying, but i dunno... thnx for the answer! =)

[@dibyendumukharjee8822]

Fabulous explanation. Thank you.

[@RimstarOrg]

My pleasure. I'm glad you like it. Thanks for watching it.

[@apxpandy4965]

Well explained - thanks!

[@lichang0704]

Do the bottles resonate only with speakers? Can I simply play it on my phone?

[@RimstarOrg]

To make the bottles move you need pretty high power speakers. I phone wouldn't be powerful enough.

[@lichang0704]

@@RimstarOrg Thank you~

[@irwanahmed001]

great video! thank you

[@rifkyramadhan6889]

Does plastic bottle can absorb sound or noise?.

[@RimstarOrg]

The plastic should absorb at least some of the sound, probably not a huge amount.

[@carlw]

Excellent. Thanks. Succinctly put.

[@755hp]

Okay, I’m going to try and replicate the Motordyne Exhaust on my Infiniti G35 Coupe by making Helmholtz resonators as described in this video! 😎👍

[@Ab.research]

Amazing sir.

[@CiliophoraEuplotes]

I don't know the details, but this is applied in the science of hollow body music instruments, like the violin.

[@elgenerz]

Great video!

[@RimstarOrg]

Thanks!

[@EddyGurge]

Nice animation!

[@Saxyct]

If I blow straight into the bottle, along the hole axis, no sound is produced. Why is the sound produced only at a specific angle of the lips with respect to the bottle neck?

[@RimstarOrg]

I think blowing straight into the bottle would interfere with the in and out airflow shown in the animation in this video. It's that in and out airflow that produces the sound that you hear.

[@juggernautsvaderdmunchkinland]

Interesting!! Counter clockwise rotation...from the input :)

[@RimstarOrg]

The counter clockwise direction of rotation is strictly due to the direction the bottles are pointed. Were you thinking something else?

[@RimstarOrg]

***** Yes, the process is reversible. Use sound waves to move the speaker cone back and forth, that would cause the magnet and coil in the speaker to produce electricity in the coil. And now that I write that, I realize that's a microphone. :)

[@juggernautsvaderdmunchkinland]

RimstarOrg Ahh...I was thinking the flow of electric current, which propagates a spinning field around the "flow". The air in the bottles, is essentially pressurized and exiting the bottles providing thrust. Right?

[@sperzieb00n]

***** i once read an article about the "zero blade wind converter", its a small wind turbine that has a rotating motion in high winds, but mainly draws energy from the internal unwanted resonance/vibrations rather than the rotation, when wind speeds are low.

[@webscrapingwithandy2110]

thank you!

[@arthikalexander316]

Why is the sound different when you blow INTO the bottle and why is different when you blow just over the bottle opening?

[@RimstarOrg]

I think if you blow into it then you disturb the resonance.

[@wdlang06]

amazing

[@MrTopHatZombie]

Where did you learn all the things you know about all these scientific things? What would you recommend to learn from? Any sources or reference that you know of?

[@RimstarOrg]

I originally learned from a variety of books (I still use my old high school physics textbook a lot, I used to read encyclopedias) and science magazines (Scientific American and Discover were good for broaden basic understanding, I don't know what they're like now) but now it's mostly online in both text and videos (starting with google searches). Just as importantly I learn by doing. I don't have any specific references. Every topic takes me somewhere else. wikipedia.org is almost always involved but there are always other sources too. For this video for example, I used wikipedia's page on Helmholtz resonance to get started but also have the book Notes on Acoustics by Uno Ingard which talks about that and also about the acoustic propulsion I did. I have a knowledge of simple harmonic oscillators (the spring) from high school physics.

[@lastmanstanding9389]

The symbol for the speed of sound is 'c' not V.

[@RimstarOrg]

The symbol for the speed of light is 'c'. I'm not sure what symbol is usually use for sound. 'V' is short for velocity, it's more general so I used that.

[@carolinaherrera7366]

T H A N K Y O U !!!!!!

[@CoolDudeClem]

I allways thought it was because of how the sound waves reflect of the inside of the bottle.

[@RimstarOrg]

If you're talking about how the bottles are propelled, this video isn't trying to answer that. This just talks about Helmholtz resonance and how the resonance is sustained in the bottles. The propulsion that happens as a result of it is another level of complexity that I don't have enough confidence in my understanding of to make a video. My understanding is that it has to do with the difference between the shape of the hole at the outside edge of the neck versus the shape of the inside end of the neck. On the hole side, due to viscosity vortices form and when they separate from the bottle they form a jet. The same thing doesn't happen on the inside end of the neck and so there's a unidirectional force. But I'm not sure I've understood it all correctly, so in this video I stop at the resonance that feeds that process.

[@RimstarOrg]

Oh, and I can see how you'd think it's the sound wave reflecting on the inside of the bottle causing the movement. But each cycle of a sound wave has two peaks, one is higher pressure than normal and one is lower pressure than normal. The higher pressure one is the one you're thinking of that would push into the bottle. But that's followed by the lower pressure one that would suck from the bottle. So over time they balance out. That's actually why people are puzzled that the bottles move at all, not realizing what I'd said about the viscosity and vortices.

[@kjanling]

you still didn't explain why the bottles started moving...

[@RimstarOrg]

I know. The only explanation I have is in that book, Notes on Acoustics, and it's either written at a level where I need more background to understand it fully or it's just not all there. Plus the book says it's never been quantified (i.e. while there's an idea of what's going on, the mathematics/physics hasn't been worked out). So I can only give a high level interpretation of what the book says, but no where near the level of detail for me to put in a video. That also why in this video I was careful to say I was explaining the speaker's role in the propulsion. The vague part is what happens as a result.

[@MrEleman]

It's an engine. In Water, it could be used instead of propellers.

[@nshire]

first? maybe?

[@h7opolo]

so much noise in the world. time to apply physics comprehension for capitalistic gain. coming soon. thanks.

[@MainlyT.]

No your not really doing it right cause the noise could be louder

[@X-VIPRIN]

Cheers! Thank you.

[@kurtisspletter643]

Great explanation, thank you!