Sir, I saw(https://www.youtube.com/watch?v=Y3kilRJ4BxA&feature=youtu.be) this video on YouTube, but I could not understand how this device works, Please help Sir @jtd @Ashish_Pardeshi @karnamdpdurga @G_N
Yes it is interesting that this device blocks sound vibration. It is very beneficial to block the vibration if we find fundamental of this noise blocking device
Acoustic Noise cancellation works only in a small receiving area - essentially a point source receiver. A head phone can have noise cancellation. A helmet will be a lot harder, but doable. A small box would be even harder requiring multiple receivers and speakers, and yet doing at best a partial job.
The reason is you hear sound as a composite from multiple sources, including reflections. As your ears get repositioned by head movement or walking the sound changes. If your ears are covered with headphones the sound is two point sources and a few mics positioned in the room can capture ambient sound, add them together and produce the same sound 180^o out of phase with the ambient sound in the head phone essentially cancelling out the ambient. HOWEVER the system has to know the position of your ears to determine the amplitude that is reaching you, else you will hear the difference of the ambient and the phase shifted signal i.e. poor or even worse noise.
This video is a total scam.
The very last example shown, a room with a single window out on the street, might work reasonably well. In that setting, the glass of the window is very likely to be a far more resonant transmitter (transducer, actually) of the external sounds. Placing the device in the glass could help to counteract the resonance of the glass itself.
However, the video doesn’t show the energy source. If it is battery operated, it must be pretty heavy. In that case, the adhesive used to fix it to the glass is bound to leave ugly marks, and also make it difficult to remove it and carry it elsewhere, something the video suggests is the normal purpose.
All in all, @jtd’s comments are spot on. The video is highly deceptive advertising/promotion.
Yes I also agree with this.
But let’s not consider the video we have to discuss what are the challenges to make this type of noise cancellation acoustic for home and auditorium or for school building and hospital
I have seen another video on YouTube please watch this (https://www.youtube.com/watch?v=MCW5HUkrr-o&feature=youtu.be) @vvcstemplay @jtd
What about this other video?
It reaffirms what I said. The device is so pathetic that it cannot cancel a single tone - the simplest case.
That product is a total scam. I guess they made good money fooling non-tech people.
As of now you cannot cancel noise. But you can INSULATE from noise by using sound absorbent material and acoustic absorption panels. These panels have special shaped protrusions that deflect noise into it’s own absorbent material thereby drastically reducing ambient sound. It has the nasty side effect of also reducing the sound amplitude of the performers in an auditorium. But will work nicely in a hospital, which are anyway quite quiet places to begin with. You can read about anechoic chambers, and specifically acoustic anechoic chambers.
I’m not sure what kind of human ingenuity is demanded, to solve a problem that shouldn’t be created in the first place.
The video is relevant, because it lists a bunch of human generated sounds, calls them a problem, and then proposes some more human created technology to reduce that problem.
Actually, in most ‘advanced’ countries, the solution is simpler: laws that limit the production of noise, enforcement of those laws, and subsequent evolution of technology and devices that do the same work with less noise. That’s the only reason we can call those nations advanced.
We are using different materials in auditorium and also in car factory to test noise of car.
We have acoustically good places which use different materials to block reflection of sound
These are test environments.
The problems of living spaces are what all of us face. Just for example, in the building across the wall, civil work inside one apartment has been continuing for six weeks or more. Every day, we get ear-splitting noise of stone cutting, and now that is interspersed with machine cutting of wood.
One might say, only because such things are common in cities, can one so easily differentiate between two high pitched whining sounds of cutting machines.
Why is this work being carried out inside residential premises? Because we don’t have good anti-noise laws that prevent major workshop and industrial activities from being carried out in residences.
We don’t even have good workmen rules that ensure that such labour is carried out only under properly supervised safe working environments (in which noise management, both for workers and for the general public, is carried out, with the noise suppression materials and so on that have been developed just for this purpose).
One might argue, that would push up the cost of refitting an apartment. Which is true. The extra cost would be spent towards the general well-being of society.
It would also push up the GDP, in a manner that more effectively filters down to the people who are actually producing goods and services.
Quite a high percentage of noise from such work is due to the poor quality of tools. Poorly balanced and poor quality bearings. It is astonishing that the same brands of tools in Tokyo are 2 orders of magnitude quieter. None of the tools come with dust collectors, never mind cyclonic dust collectors, adding to the misery.