Undergrad Focusing sound waves from the environment

[gensahilsingh]

TL;DR

Looking for some method to focus a variety of sound frequencies in the environment via metamaterials, parabolic reflectors, Helmholtz resonators, or some sort of device that can somewhat "attract" sound from it's regular path.

I'm looking for some method to focus a variety of sound frequencies in the environment via metamaterials, parabolic reflectors, Helmholtz resonators, or some sort of device that can somewhat "attract" sound from it's regular path. I've heard about Schumann resonance in the atmosphere and I was wondering if I could capture or concentrate those sound waves on an energy harvesting system via triboelectricity or piezoelectricity. If anyone could help me, I would really appreciate it.

 

[Baluncore]

Welcome to PF.

I was wondering if I could capture or concentrate those sound waves on an energy harvesting system via triboelectricity or piezoelectricity.

There is very little sound energy available from the electromagnetic Schumann resonances, or in the environment.
https://en.wikipedia.org/wiki/The_Hum
If the sound was far away, you would need a parabolic reflector to concentrate the energy.

 

[gensahilsingh]

Welcome to PF.


There is very little sound energy available from the electromagnetic Schumann resonances, or in the environment.
https://en.wikipedia.org/wiki/The_Hum
If the sound was far away, you would need a parabolic reflector to concentrate the energy.

Maybe I'm crazy, but due to the high amount of entropy in these different sources (louder sound results in more entropy etc.) is there a way to capture all this unused, "wasted" energy around us? I recently watched a video by Veritasium on YouTube talking about entropy. Do you think this is possible? The main reason why sound is not a feasible source to most people is due to the low energy density which is a direct consequence of the high entropy. But if something can actually attract sound to a magnet, the entropy decreases and leads to higher efficiency. Is there a way to do this?

 

[renormalize]

But if something can actually attract sound to a magnet, the entropy decreases and leads to higher efficiency. Is there a way to do this?

Sound is a wave of pressure fluctuations spreading in the atmosphere. As @Baluncore states, the only practical way to redirect and concentrate sound is with a focused reflector. But there are ways to capture and use sound energy near its source. Here's one example: Piezoelectric energy harvesting from traffic-induced pavement vibrations

 

[berkeman]

parabolic reflectors,

If you have a science museum near you like the San Francisco Bay Area Exploratorium, you can experience a focused long-range sound exhibit like this one:

https://www.exploratorium.edu/exhibits/archimedes

Maybe I'm crazy,

No, no, no. People are not saying that about you.

 

[gensahilsingh]

Thank you @Baluncore @berkeman and @renormalize for your answers.

... Piezoelectric energy harvesting from traffic-induced pavement vibrations

I have done quite a bit of experimentation in piezoelectricity, but I haven't been able to generate any substantial (as substantial as piezoelectricity can get) amounts of electricity from sound using piezoelectrics. However, I did make a little device that amplifies the motion of the piezo disc by around 10x, which results in regular 3-4V output to peaks of 60V. Of course, the current is very low so it's not very helpful. While it was good to achieve that kind of energy from vibrations, sound just doesn't make a lot of vibrations so it was not effective. I had an idea of ionizing gas so it becomes a conductor and then putting it in a box with two opposite layers (one electropositive and one electronegative) and attaching a parabolic reflector into the box, so when sound comes it's focused and makes the air particles go haywire, which makes it go back and forth between the top and bottom. This would generate a triboelectric effect generating energy, right? I have no idea how much it would generate though. What do you guys think?

 

[berkeman]

What reading have you been doing for energy harvesting from vibrations and sound? Use those search terms at Google and you may find some good references. If you have trouble doing the calculations that you read about in those references, post links here in this thread and we will help you with those calculations.