Turning Sound Into a Laser

Using non-linear acoustics, I'm able to focus audible sound like a laser. I go over some basic principals of operation, how I designed the circuit, and how you can build your own. Circuit Diagram at 1:18

Wikipedia Article:

Music:
Ice Dream - By "The Hikers"

[GigsTaggart]

I built this, so, some build notes:

IMPORTANT: Vcc1 and Vcc2 are switched in the schematic in the video! It doesn't seem to burn out the H bridge but be aware that they are labelled the other way in the datasheet.

It's not very loud if you use the H bridge and 12 volts. If you crank it up to 24 or 30 volts it's a more reasonable volume, but the 7805 is going to get really hot if you power it off the same voltage.

I tried feeding the modulated output from the 555 to a Sure Electronics 8 watt Class D amp I had, and that did work, but it introduces a decent amount of hiss. The H bridge is a lot cleaner, but it's harder to get the volume up. On the plus side it's louder and only needs 12 volts. The transducers do start to get warm running off the class D amp. It may be worth putting a low pass around 100-200khz on the class D output, but I didn't try it yet.

It's super sensitive to the capacitance. I got lucky I guess because the two caps I picked to get into the right ballpark turned out to be pretty spot on 40khz. Even adding a 1pF to it detunes it slightly. A variable capacitor might be a good idea (alongside a fixed one, you only need a few pF of adjustment). If you are off 40khz by much it becomes almost inaudible.

Anyway thanks for this CodeParade, even with the few hiccups I was able to recreate this and the effect pretty easily. It does really screw with you when it sounds like it's coming from somewhere else.

[grivar]

Super cool. Time to make a sound gun to make it seem like people are saying things they aren't.

[misaalanshori]

*"I don't know why it works like this, but I just accept it."*

[ThreeProphets]

Congratulations. You've independently prototyped the Long Range Acoustic Device

[LX]

You deserve more subscribers. honestly.

[Asdayasman]

There are cool applications for this. Given that it "sounds like" the sound is coming from the reflective surface, you could use this as a spooker in haunted houses, or as a distraction generator in military or milsim situations.

[Devilofdoom]

I would totally record fart sounds and point it at people to make it look like the sound came from them

[lithostheory]

0:24 it is not dependent on the frequency, but on the ratio between the wavelength and the hole size!

[AJarOfYams]

I’m both disappointed you didn’t turn sound into light and impressed you explained and made a focused beam of sound

[ryanbrown]

This is awesome. I think another reason it is highly directional is because you made a PHASED ARRAY where all waves are in phase. Therefore the wave peaks are constructive in front. I’d bet you can direct the sound electronically by shifting the phases of the different stealers to change direction. Look up phased array radar.

[neumanngregor]

At high volume, you can damage your ear drums even if you don't hear, remember that your ears are exposed at the waves in the air. BTW that is why you don't see something like this on big. At the level you output is not different from a live performance, won't get you deaf but i say DON'T CRANCK THE OUTPUT POWER UP, is for your and others good. Very nice to see someone revive this old tech. 👍

[integza]

This video idea is just awesome! I sincerely don't know how this hasn't gone viral yet! I'm spreading this on Reddit ;)

[HYOKSU]

Nice result. What really makes it directive is the array. It is clever of you to modulate the sound to unltrasound freq. so that the BW to centre freq. is so small. Only then you can apply array theory and only then forming those speakers with separation of half wavelength of the carrier freq. (Ultrasound freq.) you get high gain at the bore sight while very little power going in other directions.
Try changing the phase between speakers and you can change the main beam direction.
Good work and well done👌

[cometaHavoc]

Me: Hey can i make music?
CodeParade: NO
Me: Why?
CodeParade: SOUND IS A DEADLY LASER

[rosly_yt]

These seem really useful in an arcade setting, where every machine wants to be blasting sound, but where you don't customers to be overwhelmed by said sound.

[jonathanfields]

Now make it a phased array where you can point it in many directions. This is cool stuff man. Subscribed for sure!

[SianaGearz]

I don't know how i missed this, this is the best thing i've seen all year! Not because it's useful, but because it's so absurd, so simple, and apparently even works!

[connorcriss]

wtf you're more underrated than captaindisillusion

[Minihood]

When thinking about how high frequency waves don't spread out as much, it's better to think about the wavelength.

When a wave passes through a slit, it diffracts at the edges, you can sort of imagine this like a friction slowing the wave as it brushes past the walls on each side, which causes it to turn as it passes through, and on the other side is spreads out in a growing semi-circle/-sphere.

If the wavelength is much smaller than the width of the slit, this is analogous to making the slit much wider. For a large section of the wave in the centre of the slit, it's as if there were no walls and it is travelling in empty space. The vast majority of the sound is able to pass straight through without diffracting.

[deckard]

This is incredible: this could be used to send messages to anyone nearby, without anyone noticing, as long as so can send a canceling soundwave to all other people around (preferably not a large amount of people)