Is it Possible to Trap Sound?

Just like air and water, can we possibly trap sound in a container, I guess we can!

Few days back I was watching some videos, in one of them, I saw a guy who has a collection of air trapped in few plastic bags and labeled as years, he took one bag of 2017, opened it and inhaled the air, and all the memories of 2017 started playing. In that moment I felt some nostalgic vibes too, but suddenly a thought struck my mind, as this guy trapped air in these bags, can we trap sound?

Something like this

Researching on the Internet was not that helpful, then I proceeded to books and old Research Papers, and found few things.

As we always do, first we need to understand how the sound wave works.

Sound is a wave, it doesn’t stay still, it always propagates through the vibrations of particles present in air.

A propagating sound wave

So, by now it must have clicked your mind. No! we cannot trap sound in a container. It is not possible to trap something which is moving, right?

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But there are few ways, there’s always a way, we never stop trying, the first one is:

1. Isolation Chamber: Building a thick, dense sound-proof box can create an environment where sound can significantly be trapped within the box. There is one more “but” in this case, the sound wave will hit one surface of the box, then it reflects, and again hit another surface and again reflects, and after few movements, the energy of sound wave will all be transferred into the form of mechanical and heat energy. Hence, there’s no sound in the box. Well, technically sound didn’t escaped, but still, it’s not there in its original form.

2. Anechoic Chamber: It also has the same process as the Isolation Box. Different thing is that this chamber is made up of foam, unlike the above, it doesn’t allow the sound to reflect and lose all sound energy, instead it absorbs the sound energy and converts it to heat energy.

Anechoic Chamber (Fun Fact: You can even hear your blood flowing in the veins, inside this chamber)

3. Helmholtz Resonators: Same process but specializes in trapping sound waves with different frequencies.

So, overall, the simple conclusion is, NO! Trapping sound waves in its initial form is not possible. Well, how can we trap something which propagates.

Even though, Scientists and Engineers never stopped trying, there’s a way, using the above processes but again it wouldn’t be fair. The way is to place a sound producing object in the box, this way, there always be a way to trap sound permanently, but that would be cheating, isn’t it?

Let’s see if we invent some device to trap a propagating wave. People might ask, why waste time on something like this? Unlike previous blogs, this actually doesn’t have any applications. Yeah! this time, people are right, there is no proper application or use.

Well, let me show you the bigger picture, our main goal is not to trap sound waves, our main goal is to trap THE GRAVITATIONAL WAVES.

Will continue on this, in the upcoming blogs!