Active Noise Cancellation

[@greglantz9494]

Wow. This youtube learning content is extraordinary.

[@andycortes2085]

I love youtube and this video ! haha

[@garyha2650]

Surely raising intelligence worldwide more and more as time rolls on

[@Coneman3]

Yes it will be useful for my project to make my own speakers.

[@tuberroot1112]

Nice intro to the basic audio concepts but the single frequency "noise" is totally artificial. The amp will have different phase delay at different frequencies as well as differing amplitude gain with frequency ( not to mention the mikes ). This will do little in practice with a real sound source.

[@laurabrown3007]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" it actually Block outside Noise coming from Windows. Check Here: livesoundproof.com/best-soundproof-curtains/

[@rickbailey7183]

9:00 One of the best physical demonstrations of phasing I've ever seen! Well done video, and subsequent transference of knowledge.

[@laurabrown3007]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" it actually Block outside Noise coming from Windows. Check Here: livesoundproof.com/best-soundproof-curtains/

[@oturgator]

It is very rare to find high calibre content like this one anymore. This is pure gold.

[@occamsshavecream4541]

Yes, I can actually learn something!

[@cv462-l4x]

This is a standard approach used in Active Noise Cancellation headphones. Nothing new

[@oturgator]

@@cv462-l4x Ah! So we read a book and become as experienced as the person who can actually apply it.

[@batbawls]

Easily one of the best channels on KZbin

[@TechIngredients]

Thanks! that is a really nice endorsement..

[@laurabrown3007]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" it actually Block outside Noise coming from Windows. Check Here: livesoundproof.com/best-soundproof-curtains/

[@SRWC417]

I work for a sound company manufacturing theater speakers and haven't come across anything this amazing. Thank you for you research and incredible explanations!

[@TechIngredients]

Thanks! Check out our earlier two videos on the distributed mode loudspeakers, DML panels. These may have some applications for large venues.

[@yetifanuk]

This guy is restoring my opinion of humanity, love the idea that there are other audio nut in his garage tinkering. Big shout from the UK.

[@stevethea5250]

Technical Director - Environment And Advisory'Flexible working practices are NOT SUPPORTED'Brisbane, Queensland, Australia1 to 2 years in the role, former employee The good things Access to large scale projects The challenges Slavery to utilisation rate. Poor work/life balance. Level of expertise of senior staff is low while charge-out rates are high making it difficult to win work

[@CascadiaStronk]

"is restoring my opinion of humanity" How to spot a pompous ass that unironically thinks he's above everyone. Get a grip kid.

[@thelegendkillersshittyduff1335]

@@CascadiaStronk most of humanity is show we need a genocide is that better you pos

[@gorkyd7912]

@@CascadiaStronk Haha, moment over I guess.

[@BlockDesignz]

Extremely well explained. No images or diagrams needed, just clearly thought out wording!

[@joseb.junior1455]

Thanks KZbin suggestions, you were a good boy this time.

[@EpicGamer440]

Next on recomended: "Goomba by Takashi69"

[@laurabrown3007]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" it actually Block outside Noise coming from Windows. Check Here: livesoundproof.com/best-soundproof-curtains/

[@dishsoap5554]

Kinky

[@gilligancharliebrown399]

I've been fascinated with the concept of active noise cancellation ever since I first heard of it many years ago. You made understanding it's mitigation so simple and I truly appreciate it. Thank you for all your efforts and subject matter.

[@jdy5556]

Finally, someone who can speak and explain things in a straight forward manner instead of stumbling over words and inserting "umm" between every few words. Thank you for sharing your knowledge.

[@dinnae]

I learned so much. Thank you for taking us through the entire theory behind this from beginning to end

[@TheRealFLAMP]

this video caught me off guard, it's so genuine and informative, clearly explained and never went into the weeds. this guy is great

[@TechIngredients]

Thanks!

[@joshpayne4015]

SO REFRESHING to have a KZbin channel with someone who actually has something to say! Love your videos.

[@TechIngredients]

Thanks!

[@thesuntzu]

Best description of phasing I’ve ever heard. Amazing stuff. Stay warm up there!

[@bclements5447]

Amazing live demonstration of both physical and electrical phasing of sound to cancel out unwanted noise.

[@TechIngredients]

Thanks!

[@Caminovan]

I am amazed how efficiently the guy explains so complicated topic in so simple way. THANK YOU !

[@glenaw]

Very nicely done. I will be building a cnc machine with a enclosure and this gives me a lot of good information on how to make it even quieter. I would like to offer my compliments on your knowledge and your ability to convey the information with such clarity and understanding

[@TechIngredients]

Thanks!

[@dexagalapagos]

Who is this guy that he knows so much about everything.... I can't stop watching these videos.

[@ramheyhey]

Thanks for teaching a young engineer about some awesome things!!

[@TechIngredients]

In the words of Morgan Freeman, "Pass it on".

[@_next223]

This is definitely the most thorough and quickest bestest understanding of sound and it's awesome. great job

[@_arrgh976]

The 600 speaker 26,400 watt "Wall of Sound" built in 1974 by Stan Owsley used this technique to eliminate the feedback from the microphones on stage. Each mic had a second mic 180 degrees out of phase two inches apart or so. Vocals went into the top mic about two inches above a lower mic, the second mic cancelled the sound on stage: no monitors! The sound quality at Dead concerts was superb; almost 600 meters away. The show could be heard 2 miles away! Not bad for 1974!!

[@tophan5146]

Fascinating

[@Oli420X]

That's mad, thanks for the fact!

[@PatTagudar]

Very cool 😎

[@pedrocavaleiro3688]

Although most of it wasn't unknown to me, your ability to synthesise and maintain the simplest line of thinking makes this a teaching gem. Thank you for sharing!

[@deadbolt91765]

As I listened to this in my truck, I found some standing waves during the demonstration part of the video. Moving my head 6 inches from the driver seat made the sound much quieter. Pretty cool secondary demonstration of the impact of interacting pressure waves

[@Oli420X]

Tbf, that depends on the speaker setup in the car. If you had one in each door for example, not only will the rear speakers interfere but the fact you'd have to move left and right changing your distance between the speakers not back and forward. I'm not calling you a liar 😂 just saying results may vary depending on the car.

[@berniestep]

Well - structured discourse; exceptionally clear explanations of the theory; precise, technical demonstrations - Brilliant! This guy should be government-funded he's so good. Thank you!

[@rasmus9311]

Very clearly explained 👌

[@18deadmonkeys]

Phasing is the reason you want to stand directly in front of the sound control at a concert. Everything is focused there, and if you stray to other areas you'll find "dead spots" where degrees of cancellation happens. Also you might notice that the music might not be in sync because sound travels so slow, so the signal from the further speakers reaches your ears noticeably later than the closer speakers. For a better sound experience, don't rush to the front of the crowd, get as close to center as you can.

[@frodev728]

Negative. The explanation of what sound is was actually pretty terrible.

[@DrumFFx]

i was having trouble i loved the part about dual foam steel construction absorbing both high and low frequencies it makes perfect sense.. but "phase" and cancellation occurs when the net wave is zero. It is way more effective to describe audio/noise cancellation as a wave with a positive and negative poles. polarizing or flipping the wave will leave you with a net of zero. side note: not having recording devices equal distances from the source creates a loss of phase strength in this same regard

[@pedroferrr1412]

@@frodev728, actually it was a very good explanation, to visualize better, imagine bars, instead of a wave.

[@matejzatko2085]

I feel like you make simple things seem complicated. But at the same time you are the only channel that uses practical examples.

[@TechIngredients]

I try to do the opposite. It is important to be precise in understanding simple principles, otherwise you will be unable to build on that foundation.

[@BunniBuu]

This was absolutely beautiful! You can learn so much about sound from this video :) However I would like to point out that there is ONE MORE passive noise reduction technique that was not mentioned! The shape of the box! While a cube is very effective for active noise reduction, since you can more properly pinpoint the waves to invert, having angles in which the sound almost slides off of will reduce the vibrations of the outer layer significantly. This isn't useful in this scenario, as you know the source of the noise, but not the location of the listener. However, if you know the location of the listener and not the location of the, source of the noise it can be very convenient! This is why sound-proofing walls for musicians and theaters tend to have triangular structures to 'trap' the sound, letting it vibrate all that it wants away from the listener. Alternatively (or supplementarily) they will have curtains to 'catch' the vibrations and reduce echo~

[@benhurj]

Very interesting point, do you have a background in sound engineering?

[@BunniBuu]

@@benhurj I wish. I have a background of music and have studied heavily in acoustics (specifically for microphones and on-stage settings for music), but I'm not very knowledgeable in terms of technology outside of Digital Audio Workstations

[@nypry]

Thank you for taking the time to explain those concepts without skipping "obvious" ( to experts) steps. This is the perfect format for learning on youtube, complex enough to require your listener's full concentration, yet simple enough to not get lost.

[@TechIngredients]

Thanks! We got the target.

[@siimkask14]

"LAAAAAAAA" caught me off guard

[@erkhembayarenkhtaivan2630]

LUL

[@Electrohedron]

'O sole mio!

[@PassiveDissimulation]

I read this right as he said it. Eerie...

[@SanHydronoid]

Pretty much

[@laurabrown3007]

One of the Best Ideas of SoundProofing is "SoundProof Curtains" it actually Block outside Noise coming from Windows. Check Here: livesoundproof.com/best-soundproof-curtains/

[@brandenwaite]

I have had an idea for a long time for a specific use case, and your work will get me closer to my prototype. Looking forward to the next videos.

[@TechIngredients]

Good luck! More incoming.

[@brandenwaite]

@@TechIngredients Question for you and your dad... First of all, I am one of your biggest fans for sure... Maybe I'll post a Short on my solar heater, and "world's best speakers" hanging from my room ceiling... both partially inspired by you guys. The idea I mentioned I have, may not be the most profitable idea but it's likely decently profitable... Patentable-i'm pretty confident about that-. I won't be able to get any of my so very many ideas off the ground without help, mentorship, older wise advisor... or something similar. Maybe we could come up with an agreement and collaborate on it. I'm willing to sign over whatever profits to you two, in order to get a tiny bit of passive income, all said and done through licensing out or outright selling the patent. I just gotta start making my ideas reality, and no one close to me that I ask knows what to do with my ideas. 🙏🏻

[@Ben_Cheng]

Thanks for the informative video! Could you demonstrate the same experiment with other noise sources please? For example, perhaps some music or random noise. Would like to know how effective it would be for a non constant signal!

[@timothy1024_]

Stumbled on to this channel in a search feed. Best channel I have ever watched. Thanks for the education!

[@TechIngredients]

Glad you found us. Thanks!

[@BurstNibbler]

Very intelligent bloke.

[@wolfram77]

Smart people always look for improvements!

[@freelectron2029]

So your one of those people who think complicated descriptions translates to intelligence.....

[@JordonBeal]

@@freelectron2029 that wasn’t a complicated description. That was a very clear and concise explanation and demonstration of phase, polarity, and active noise reduction wrapped up in less than 20 minutes. Most audio professionals couldn’t pull that off. So, yes, intelligence.

[@freelectron2029]

@@JordonBeal if you think that wasnt complicated than you to have fallen victim to the engineer mentality. there are far more simpler ways to describe that. so no, not intelligence. its just the difference beteewn an edited script and an off the cuff explanation that you are comparing. so you are not intelligent as you didnt realise the two differences in the thigs you were comparing. so no, not intelligent.

[@pr4tn065]

Sir, dont know how I stumbled onto this video but I watched it all......twice. I am looking for a solution to a problem and I think you may have helped me solve it. It may change my life and that of my family. Being super serious, now I gotta figure out how to make it work or if its even possible. THANK YOU THANK YOU THANK YOU. About to watch it a third time.

[@funny-video-YouTube-channel]

*Make one for the window* and save the world from traffic noise. The vibrating window is the source of much noise in the home at night for the people who live near roads or airports. It's possible to make the glass to vibrate less with this type of setup.

[@samheatley1883]

Theoretically, yes it's possible but because glass is so brittle it wouldn't be efficient and it could possibly shatter due to a large noise, also you would have to put up with the system right in the middle of the window (If you care about your view).

[@dvinnyq2889]

Helium

[@ArtemisKitty]

@@dvinnyq2889 Yup, just what I was thinking. What about a "decompression chamber" (Is there a proper term for this? Anyone? Help?) between panes of glass comprised of a low-density gas like helium? That would deaden a lot of the sound just by not having enough molecules in the space between panes to push around. I feel your pain if you live near an airport, as I grew up under the secondary flight approach vector for a large international airport that they used when there was bad weather. One observation I've made is that larger aircraft engines produce a much deeper tone, a sort of rumble that shakes the very framework of the house and uses your roof/attic as a sort of sound amplification chamber when anything the size of say a 727 or larger is on final approach. At takeoff, the higher frequencies spike in intensity, but on landing approach, I don't think silencing the windows would be enough. Just my $0.02 though, love the idea. And yeah, even so, the helium idea would probably work great for takeoff/flyover paths. Just not arrivals, so much, I think. Still a great possibility for ~80% of the people around an airport, I'd imagine.

[@94ToBor]

How about trying to combine this with the panel-speakers? As they distribute sound better, and are cheap.. Placing a microphone on the outside of a window to reduce feedback, and the speaker next to the window (on the inside). Applied science has a video where he shows how to convert a window into a microphone using a laser and an optical receiver.. Headset with active noise cancelling is my current solution, altho I prefer sleeping sideways.. Considering making a pillow with a hole for the cups, but this sounds cooler!

[@jb9282]

The noise is a not correllated signal! 😀😆 is not the same like an Sinus-Signal from Generator

[@chevy6794]

Very interesting. I came here because I have an older diesel truck. Dodge did a excellent job of removing cab noise but the engine is soo loud you have to turn it off to talk outside of the truck or in drive throughs. I would like the cab a little quieter especially on long family trips with the load of our trailer. I already had an idea how noise cancellation worked but thought I could simply have a microphone under the hood and an out of phase speaker in the cab. You made me realize it’s not quite that simple. Thanks for an informative video. I see some small 2t engines in the background and it looks like you do some interesting stuff. I’ll be checking out more of your channel and possibly subscribing. Thanks.

[@hushhash]

You're a great teacher and the video is great. I would have loved for this video to have a demonstration of loud music in the box instead of the generated tone and also am very interested to know if you ever continues hacking it.

[@lehlohonolomahlong3075]

The quality of the content on this channel deserves more subscribers

[@TechIngredients]

Thanks!

[@emremutlu44]

You got extraordinary explaining skills with very clear phrases Sir! *Thank you for making this video.* Liked & Subscribed! I have a question, Sir. I could not help myself thinking that, if you want to stop the noise within a box, why using a vacuum shell structure is not an option? for practical purposes? Another question, is it possible to cancel the noise coming from a source by projecting phase-shifted sound right to the source (feedback from a mic in the pathway of the sound and with a proper delay), without keeping the source in any kind of box?

[@TechIngredients]

Yes. A vacuum is the ultimate solution. It would be even better than hydrogen or helium (take a look at those videos). The heavy structure to support it is the deal killer.

[@CallMeHector]

Boy, I was looking an explanation for Noise Cancellation and this vid is just so well explained. I found a gem on YT

[@claudbase]

I believe that there is one more variable that could be used to increase the wall rigidity: the actual wall shape. Curved walls would be more rigid then totally flat walls (cylindrical or spherical sections?). Also, searching for specific walls geometries with no or little resonance in the frequency range of the noise generated by the engine might also help.

[@paulthomas5860]

As in bose original wave guide that produced ‘big’ sound from a small box. Plus, the geometry of a heat sink, fins to inside giving more surface area to trap/break up waves plus vibrate at à frequency that produces heat vs audible?

[@KristoZ]

Amazingly well explained and the host speaks very clear and straight to the point.

[@triple151621]

Stephen Colbert has really gone rogue here.

[@deckmonkey1459]

On the next episode, Stephen will use noise cancelling to cancel Trump.

[@RupertBruce]

Similar accent and glasses?

[@thoraero]

Great lecture. This is the best noise reduction guide I have seen ever.

[@Doctorbasss]

Thanks again for that great physics video. Very informative/instructive. In teh next video you could also talk about helmotz reasonator. Those cavity delay the phase that become itself cancelling his own source. but as well it only work on a single frequency and few harmonics.

[@ericbrooking]

A Helmholtz resonator is like blowing air across an empty bottle, the length of the tube and the volume of the cavity set the resonate frequency. Here he is trying to cancel multiple frequencies. Without an adaptive algorithm, the highest frequency that he can cancel reliably will depend on the distance between the mic and the exciter (speaker).

[@ericbrooking]

I should also point out that a Helmholtz resonator is the idea behind ported or vented enclosures. This adds two poles to the high pass response transfer function of a bass driver and can therefore influence more than just one frequency. It can pull up a large section of the response curve giving you more bass response at the expense of more phase shift.

[@ALO_x_Z]

Exactly what I needed!! KZbin's search algorithm sucks for making me scroll past that many videos despite me searching for "active noise cancellation explained"

[@TechIngredients]

Great, and welcome to our little slice of paradise.

[@beflabbergasted325]

In 1990 Lotus used a noise cancellation technology on their Lotus Esprit. Lotus researchers mounted microphones, which monitor noise, in the car's passenger compartment and feed the information to a small computer. The computer analyzes the sound and produces a signal, through the car's stereo speakers, that is identical in pitch and volume but reversed, so that the peaks of its sound waves coincide with the troughs of the original noise, effectively canceling most of what is known as the resonant boom. The anti-noise signal is not audible on its own and does not interfere with music reproduction. ''The first patent was filed in the U.S. in 1934,'' said Malcolm McDonald, general manager of noise, vibration and harshness for Lotus Engineering, the research and consulting unit of Group Lotus, the British sports car company. The procedure had been made possible only after a few years by ''advances in digital signal processing and the modern digital signal processing chip,'' Mr. McDonald said. He added, ''We are using not just one speaker, but four or six and feedback from six microphones; it's the ability to process that all very rapidly which has made it possible.'' Today, Lotus has Halosonic which comprises of a suite of four Lotus patented Active Noise Control technologies that enhance the in-cabin audible environment and improve pedestrian safety along with Road Noise Cancellation and Engine Order Cancellation actively control refinement levels and minimise undesirable low frequency noises.

[@tarzaan2603]

Cool, thanks!

[@landroveraddict2457]

Super interested in this subject cannot wait for the next update. There are so many bad science channels on YT it is very refreshing to listen to someone who really knows science. Thank you.

[@TechIngredients]

Thank's a lot!

[@carlfranz6805]

Brilliant... however, since I'm listening through a low res source (cell phone) the noise level changes at the end were gone. Some sort of measurement value display would have helped... Sorry, poorly put but I'm still on my first cup of coffee and a bit fuzzy from a long night of tax forms.

[@fredwells7403]

You know you're a drug addict when you excuse your clumsiness/haziness by saying "I'm only on my first dose guys, it hasn't quite kicked in yet, give me a chance" 😂 I'm not bashing the use of any kind of drugs by the way, I myself do indulge in coffee, alcohol, and cannabis. It's only human :)

[@workhardism]

Another unfortunate martyr of our punitive tax laws. Smh. LoL.

[@charlesmorris100]

he was playing high frequeny, phones play that well. its the base or lows that phones are bad at

[@arnoldrimmer9161]

You have taught me more in 16 minutes than my teacher did in 5 years, very very interesting and very very well explained. 👍 top man!!

[@TechIngredients]

Thanks! More on the way.

[@obsoquasi]

Parallel walls amplify certain waves (standing waves). So maybe a box without parallel sides would be beneficial here. And also, I think this type of rudimentary noise cancellation won't work as great for non-linear / noisy sound / non-repeating waves. But that's maybe not a huge issue for motor sounds. What is an issue however is that a motor will produce many different sound waves - which probably aren't all part of one overtone spectrum. So the cancellation can only focus on some of these waves while not working well with others or even increasing their amplitude. It would become much more complex if each wave would be tackled individually with a FFT and resynthesis approach, but it would probably be more effective. Going to watch your follow-up video now...

[@TechIngredients]

I suspect non-parallel walls will help to some extent. You are correct that this is not a sophisticated, FFT approach which would undoubtedly would be more effective (and more complicated). For reducing the sound of a fixed and relatively predictable spectrum this may not be too bad. Another, less computationally intense approach would be a much larger number of small voice coils paired with 1D accelerometers. The feed back loop would minimize accelerometer signal locally. A high bandwidth of at least 10x the intended damping frequency would likely work pretty well.

[@NicleT]

John Flury exactly, in sound engineering we avoid parallel surfaces like walls and glasses. Then even absorption materials like foam, wood, fibers, etc. are shaped in multiple angles and sub angles in them too. You want sound waves to move away from direct reflection and drive them to absorption matter. This is a base setup concept in most studios and dead rooms.

[@EliSpizzichino]

@@TechIngredients can you elaborate on this idea of using 1D accelerometers? I'm not sure I understand what you're saying

[@TechIngredients]

The accelerometer will act as a microphone does to convert the displacement over time into a signal that can be amplified to drive a voice coil to resist that displacement in a feed back loop.

[@EliSpizzichino]

@@TechIngredients do you think it'll work for not steady waves given the delay to process and react to the signal? You have to use an MCU to read accelerometers.

[@SgtJohnRemairez]

When I hear my science teachers speak I fall asleep, but when I hear you explaining the science behind things it really fascinates me. Maybe its my environment or your charismatic voice, I do not know but I really love this channel :)

[@TechIngredients]

Thanks! Look forward to seeing you.

[@Papaya_]

4:08 “acoustic laser” sounds like a great band name

[@oshJJhos]

Bautiful to see somebody explain something that he has naturally and completly understood!

[@TechIngredients]

Thank you!

[@BurstNibbler]

I like the demonstration of active noise cancellation but how does one deal with the multi-frequencies of an engine? Using the microphone, it can produce feed-back to the amplifiers to drive the wall mounted actuators but surely different frequencies picked up would require different amounts of gain (which would I guess have to be a trade off to some respect)?

[@BurstNibbler]

Ah I should have read the comments in detail first, it seems engines are below 1KHz so the entire envelope of sound can be contained somewhat efficiently. And of course if the sound from the cancelling actuators is 180 degrees out of phase then no matter what the frequency is, then as long as the frequency response of the driver material is capable of producing then it will cancel the full range (somewhat) Thanks!

[@feschber]

Look up Fourier Transformation. 3blue1brown has a great video on that

[@fredwells7403]

@@feschber the fourier transform is kind of unrelated to his question

[@JasonDelaLuna]

I like the way you explained things specially when you back it up with practical examples to expound a better description.

[@MarkProffitt]

Another degree of freedom is shape. Stealth aircraft use shape to disrupt reflections.

[@Steve211Ucdhihifvshi]

Shape has more to do with radar reflection than sound, but good point.

[@asherpa4u]

Stealth (to a degree) re-directs (mirrors away) the energy waves from being reflected back to an observer. Think of light waves for example... shine a spotlight on a plane at night, but the plane is coated in 'special mirrors' that, (because of magic) let NO light pixies to EVER get bounced back to an observer. not even the smallest pinprick of light. From the observer's point of view, his spotlight is just going into outerspace (just like everywhere else in the otherwise empty, dark skies). Schnook ;--)

[@whythesenotes-adventuresin5576]

Excellent video and very well explained. I agree with Mark Proffitt - shape is another degree of freedom, in two specific ways. Low frequency sound waves behave much like water waves - they "build up" in certain places. A cube is actually the worst shape for acoustics because every dimension is the same, so the buildups will be in the same frequencies in all dimensions. You can mathematically calculate the frequency buildups very easily - he gives you all the math you need in the video. Wavelength is the speed of sound divided by the frequency - sound moves at 1130 feet per second, so a 1130 hz wavelength is 1 foot long. This makes a 1 foot cube the worst shape you can make because the buildup of sound pressure will be significant, and will be the same in all dimensions. If you vary the length, width and height, you can change the - they're called modes - axial modes (involving two opposite surfaces) so that they don't all build up at the same frequency. To visualize this - fill up your kitchen sing or any square vessel with water & start pumping the water with your hand. Eventually you'll see that the shape of the sink strongly influences the size, shape and location of the waves. Additionally, you can measure the frequency output of whatever device (engine) you're putting inside the box, and then craft the box so that it doesn't emphasize those frequencies - if it outputs 500hz, then don't make the box a multiple of (1130 feet per second / 500 cycles per second = 2.26 feet). There are many calculators online where you can plug in dimensions and it'll spit out the frequencies that get emphasized - google "room mode calculator". High frequency sound waves behave much more like light - they reflect. It's difficult to tell where a woofer is in a room, but you know where each tweeter is & depending on nearby surfaces, you get phased reflections that reach your ear at the same time as the sound. To break up high frequency waves you can use "digital" diffusion, which behaves like frosted glass. Rather than light bouncing off at a predictable angle because the surface is flat, you texture the surface so that the sound bounces off in random directions. The size of the texture is based on the frequency(ies) you want to diffuse. Another method for sound reduction - known to the Ancient Greeks, they put them in their theaters - is a Helmholtz Resonator. You know how if you blow wind over a bottle it makes a sound? Well that shape absorbs sound at that frequency. If you know the problem frequencies, you can build a Helmholtz Resonator to absorb that frequency. This is similar to the way cities try to build shapes into the ocean floor nearby to reduce the power of strong waves. A combination of the above - vary the shape of the box, create rough surfaces on the walls, and add tuned acoustical traps as needed/desired can do a lot to minimize sound transmission (along with all of the things you discussed). Lastly, similar to a vacuum thermos, you can create a "room within a room" or a "box within a box" to reduce the direct vibrations reaching the outside. This is intuitive based on your excellent discussion of sound transmission through substances of various stiffness. A sort of "laminate" of stiff/absorbent/stiff/absorbent will work very well to reduce sound transmission out of the box - you may be better results with thinner materials but sandwiched in such a fashion than with thicker materials that are not sandwiched like this. These are all passive noise reduction techniques that you can employ before getting to active noise reduction - which you use is a matter of your end goals and design constraints.

[@noobface777]

You had my full undivided attention for the entire 16 minutes, thank you sir.

[@JamesHastings2008]

10:55 Mind Blown! He went next level!

[@Oli420X]

This man does things very far beyond me

[@cmonkey63]

Thanks for what is essentially a university lecture, and engaging at that. I own two pairs of noise-cancelling headphones but didn't know how they work, until now. Thanks!

[@kyledavidson8712]

From now on I will only use a bench vice as all mic stands.

[@PcPete123]

A great explanation and demonstration of combining passive and active noise suppression. I worked for an MOD supplier that pioneered this technology and manufactured it for use inside airplane cabins. One of its many uses..

[@cokecl]

I was waiting for him to test it with another sound rather than a pure signal☹️

[@LaCinturaDiOrione]

he did not... because that would have been a disaster. This is just a laboratory experiment. this setup will never work with a real engine. or more complicated soundwaves.

[@marcelotai1055]

Mainly because of budget constraints. I believe... (Also, for practical reasons, we don't need complete sound cancelation. A strong attenuation would be usefull enough).

[@cokecl]

Rygel Orionis I want to see how good or bad could it be

[@Linrox]

The ironic thing about this video is you clearly understand how to reduce and counter the noise but your nieghbours are still annoyed by your noise. Love the video

[@bitsurfer0101]

I'd like to use this idea to make my 3D printer quieter since I live in an apartment.

[@pj7362]

Im just going to take this opportunity again to thank you so much for your gift of education. Truly fascinating and I am thankful for it.

[@gerry343]

2:36 Speed of sound is about 1100Hz ? I thought Hz was a unit of frequency.

[@TechIngredients]

A verbal typo. I should have said, 1100 feet/second.

[@carabooseOG]

@@TechIngredients A speecho?

[@andrewsimpson6756]

@@carabooseOG YES!

[@seerking]

A unit of frequency that cycles. An energy cycle. Energy is movement.

[@simongitau6962]

Time is inversely related to frequency which is inversely related to speed thus making speed directly proportional to frequency hence they both increase and decrease together

[@WhatDoRealProsUse]

This should be used in all home appliances, all heavy tools, all motor vehicles and so on, to finally reduce the noise pollution on our planet. Great video, great explanation, keep it up!

[@TechIngredients]

Thanks!

[@josephf151]

Great video, now how would one apply this to a noise source such as those nitro engines you will be using? From what I am thinking, If you were trying to do this real time, you would have to be able to read the incoming frequencies across the entire audible section (or designated peak sections), and then on the spot be creating the 90 degree phase shift equivalent for each of these frequencies and deliver it. For lower frequency noise you would have milliseconds, but for high frequency noise you would be looking at around 1/20000 of a second. I guess a strong micro controller might be fast enough to at least tackle such cancellation up to around 10KHz? I guess the low frequencies would be most important as they tend to travel further?

[@TechIngredients]

The large majority of the noise from the gasoline engines is below 1kHz. To avoid the complexity of adding a spacing factor and the associated phase delay for the higher frequencies we will low pass filter the microphones above 1 kHz. The distance between the microphones and the audio exciters is 1 cm, therefore a simple 180 degree phase shift should suffice.

[@josephf151]

Hmm, if you only have to worry about up to 1KHz, then that seems a lot more doable. This whole channel is a gold mine of information on things I never really bothered to think that much about.

[@RinksRides]

a humble arduino Atmega328 is capable of reading analog up to 70KHz without degredation & if you dont mind +/- a few LSB's up to 200KHz and change is possible. But to also do something like FFT with an 8bit controller, well, just dont expect much.

[@CalebMcLellan]

There should be no latency with the playback audio as there is no need for a logic circuit or digital processor. All you will need to do is invert the polarity of the incoming noise and play it back at the same pressure level and make sure the placement of the microphones are equidistant from the source as the playback speakers...

[@raykent3211]

Caleb McLellan you make an important point, but it is only true for linear, parallel phased waves. If waves are radiating from a point source there is no other single point in space which allows you to cancel them in all directions. Expect interference patterns which reduce the intensity in some places and increase it in others. You'd have to surround the source in a spherical shell of opposing transducers. Not practicable. Well, if we're talking about the sound from the exhaust of an IC engine it's quite easy to provide the anti sound signal to reduce that, in the way described here. But doing that involves putting opposing pressure on the exhaust which reduces the efficiency of the engine. Compared to a conventional silencer..?.. well , I await the data.

[@wusluf]

Thank you for this exceptional content. Not only is the presentation spot on your way of speaking and explaining creates an urge to learn more. You have all the necessary details and they are explained in a minimal but surprisingly comprehensive way. Hope educators around the globe will be inspired by this content, would have loved to have such an teacher back in the day.

[@TechIngredients]

Thanks!

[@CurtisMommsen]

Wouldn't a 4th degree of freedom be a vacuum?

[@CurtisMommsen]

Chickenbone Genome doesn't really matter if there's no medium.

[@CurtisMommsen]

Chickenbone Genome well that's exactly what Yeti does with my coffee every morning...

[@Dude31463]

Curtis Mommsen ... Very good point... That's why they say "No one can hear you scream in space." HA! I don't know who "they" are btw... :)

[@VHflyboy]

Tell us more about this internal combustion engine that runs in a vacuum :p

[@CurtisMommsen]

Drop a lit match into your Yeti. It will continue to burn (unless there's coffee)

[@jhonnyspeed4513]

This channel is phenomenal. I feel like I just went through a semester of college.

[@RyanLackey]

Why couldn't you also use geometry as a fourth way to reduce sound? If you could angle equally stiff/massive materials to send reflections into long traps, you'd win, at least at specific frequencies/temperatures/etc. You could also set it up for destructive (or constructive) interference if you really wanted, for passive sound cancellation or reinforcement.

[@fookingsog]

Ryan Lackey High end speaker enclosures use trapezoidal or non-parallel enclosure walls to reduce/eliminate internal standing waves or certain resonances with internal baffles & bracing!

[@JesusisJesus]

Ryan, further to what fook said, Look up what a "W Box" is. It's a subwoofer design that does pretty much exactly what you are asking about.

[@tonyupsman]

I am certainly no scientist but I personally have seen several automotive engine exhaust mufflers cut open, revealing just that. The angled metal baffles are arranged in a manner to reflect a great deal of the engine exhaust sounds back upon themselves to cancel them out as they are pushed through the muffler. Mind you that there are ever changing designs and materials being used to control decibels as much as possible without impacting performance through airflow restriction... Maybe they could install low cost microphones at key points in the vehicle. Using hardware and software solutions to, analyze and in real time, play the opposite waves through a vehicles speakers and effectively cancel the road noise, wind noise, engine noise, and other unwanted noise pollution from the public at large....? ok, I lied... I am a scientist. No, but really folks I dont want to go through life with ear buds crammed in my ears or wear headphones like I am a 49 year old Dj. Why cant we use existing speakers from our Televisions, Computers, Car Audio etc and just have somekind of new noisecanceling in real time firmware .... use existing microphones (Your smart TV can hear you, cellphones, tablets, pc, laptops, every car has onstar basically....voila...microphone... (a damn good one comes with onstar, its amazing how accurate)..... and just like that...... Weve got that amazing Bose active, real time noise cancelling ability they used to charge a couple thousand for to make everything go away. albeit now we can control what gets silenced, reduced volume or unaffected.... like your mother in law. She needs to know that you are getting her loud and clear. -Tony Cusimano

[@wramarante]

I'm pretty happy to see dedicated minds doing nice stuff and explaining it in an easy way to understand. Congrats.

[@TechIngredients]

Thanks!

[@tianyuez]

So this means I can put an actuatuator on my wall and silent my neighbors?

[@TechIngredients]

That depends on your neighbors.

[@drmosfet]

Love to see a how to on this

[@MrSzymonurai]

You make great videos. You don't just build you prove your build with science.

[@MarcusWolschon]

Has there been an update to this since 2017?

[@MarkTravisMusicPage]

Marcus Wolschon guessing it didn’t work

[@DIY3DTECHcom]

Wow, very well explained, never looked at as you explained however it makes sense and never thought of just flipping the leads on the speaker to invert the phase!

[@mikeoliver3254]

What about redirecting the sound upwards? Couldn't you build a inverted pyramid that surrounds APU and bounces the sound skyward? I'm envisioning something lightweight like magnesium with a felt lining. Then you don't run into overheating issues that an enclosed APU might have. Just speculating.

[@mrdavis3804]

Mike oliver What goes up often comes down.

[@Nevir202]

Mr Davis Lmao

[@Steve211Ucdhihifvshi]

Id just use quieter engines, to be honest, or look at an exhaust system like what they used on that original jet car from the 50s

[@unlokia]

Except for Apple stock... it keeps rising...

[@title1091]

That is done with exhaust in turbine's. They change the shape of the sound to be in tolerance. Doesn't get rid of it, just modifies sound to a point human don't hear it.

[@tagcapv1822]

one of the, if not the best science channel!!! better than most lectures! keep up the good work!

[@TechIngredients]

Thanks!

[@-Burs]

I need couple of these for my wife. Where can I get them? Though her voice is much higher than 11KHz.

[@Breadbored.]

lol

[@faustin289]

I think you are ok, you just have no clue about how to use your equipment. See, you have a couple of microphones (ears) to sample the noise, a powerful processor to calculate the phase of the sound and a big speaker (a.k.a mouth) to synthesize the canceling noise.

[@JustinKoenigSilica]

WIFE BAD ok boomer

[@AlphaMachina]

I can't believe I didn't know about this channel. This is exactly what I've been looking for.

[@mikeoliver3254]

So sound produces small high and low pressure regions in the air that move at the speed of sound? Is that right?

[@TechIngredients]

Yes.

[@MrGreenAKAguci00]

What wasn't mentioned in this video, lower frequencies are less and less directional. It starts around 800Hz and below. With bass frequencies being pretty much omnidirectional. So low frequencies pretty much create spherical pressure regions. That's why during concerts system engineers tend to have subs in cardioid configurations that use phase manipulation in both distance and electronical way (they tweak the timing and the polarity of the signal with sound processing and also by physically placing speakers) to pump sound out from the rear of a speaker back to the front towards audience and make the system more efficient and the stage less noisy. That's one of the coolest examples: kzbin.info/www/bejne/q6Cvdmt3q9h7epI

[@Sativic]

Excellent.

[@GotYourWallet]

I knew the basics of active noise cancelation but to see it demonstrated so well was amazing.

[@sjoerdschreiber7844]

"You can even pick up my voice, LAAAAAAAAAAAA!"

[@1asprec]

Truly amazing explanation - easily understood. I appreciate you taking time out to make this demonstration and explain the mechanics of active noise cancellation. Looking forward to the videos that you said you'd upload in relation to this. Thank you.😃

[@tbyte007]

It would have been the perfect channel if it wasn't for the ancient simple man measurements. Like donkey balls , feet, fingers, nails, stones, horse dump and stuff like that :D

[@TechIngredients]

As our testing and measurement methods and equipment improve we will incorporate them into the videos... absolutely. Many of the principles are still valid and hopefully useful, but I understand your criticism. You have a point except for the horse dump. I haven't needed to use that yet.

[@tbyte007]

Everything in your videos is useful even for people that are "fluent in science". Seeing what you know in theory done in practice is for the lack of better words - priceless. I think this channel is underappreciated - you should have lot more subscribers for such quality channel ! Just add metric system measurements too (the horse dump I guess is only needed for heavier loads so with that large drone you might come to need it !) :D

[@TechIngredients]

Thanks! Tell your friends and colleagues and I promise never to use a drachm...ever.

[@phillipmay2541]

Any Arthur C. Clarke fans remember his short story "Silence Please! " from the collected tales from the White Hart? So glad this inspiring Tech Ingredients gentleman is evidently unaffected by the First law consequences of active cancellation. And thankfully there seems to be no smoking remains in the video. This channel has got to be my next bing watch.

[@tjmmcd1]

You deserve a teacher of the year nomination.

[@DiegoSynth]

Excellent explanation, great work all of you, not only the presentation and all of its details but also the cameramen work. Thanks a lot for all of this information!

[@AdailAntonio]

One of the best videos that I watched in KZbin. Congratulations

[@TechIngredients]

Thanks!

[@JoseSilveira-newhandleforYT]

I remember, by the late 70's / early 80's, an article in an electronics magazine, about an active noise cancellation experiment in a UK industry stack, using multiple high power compression speakers from Lansing and obtaining very good noise reduction results. I was quite impressed at the time (only wish there was internet and KZbin back then, instead of just numbers in paper) and viewing your smaller scale project brings back that same sense of a problem well tackled.

[@cbobaddilla]

I found this channel yesterday and I'm very happy with the content of this video, great explanation and excite experiments! Congrats to all the people involved on it! cheers from Brazil!

[@fpm1979]

Your demonstration with the two speakers impressed me.

[@DescartesRenegade]

The amount of science that goes on in that studio is astounding.

[@tomwilson2112]

I really liked this demo, and I may send it on to my sound people for their reference. (Also to understand why it's so important to wire speakers in phase.) One note: @2:30 Herz is a measurement of frequency, not velocity. Something doesn't move at a "Hertz". It moves at a velocity, or speed. (Although yes, 1100 feet per second is about right.) When doing audio work, I will often need to set up a delay for speakers located further away from the stage. If the a speaker is 50 feet away from the stage, we add 55 ms of delay. Works great!

[@GodSpeaksInMath]

You have an excellent channel. Actually submitted a patent for a system using this type of noise cancellation as one feature and even have been working with those very same transducers which are amazing. Great work on your setups and explanations also..

[@TechIngredients]

Thanks!

[@mrg26115]

Hi ! Can you provide a link to your paper ? I would love to check it out :)

[@royalblue9017]

Thanks. One of the best learning channels on youtube!!

[@AleksandarGrozdanoski]

I knew about this principle in theory, but never heard it so well explained.

[@4.0.4]

This was an instant like and subscribe. You've explained it so well and made it fun to imagine improvements at the end! You're the kind of science educator the world needs, and a great DIYer.

[@TechIngredients]

Thank you!