Thread: How to create a very powerful sound wave?

1. Hi, Was just studying soundwaves. Ok So far i know that there's 3 components: Frequency, wavelength and Amplitude. Now i know that Frequency is Hertz and Amplitude is volume. What is Wavelength? Is it Distance? How far the wave length is suppose to go? I know it has to do with Nano meters but just want to make sure it has something to do with distance.

Also just out of curiosity, how much energy/ power in terms of voltage does it take to make a very powerful soundwave that breaks concrete and crumples metal from the inside? i know it can be done but not sure about how it's actually done.

2.

3. Originally Posted by Sci_Research
Hi, Was just studying soundwaves. Ok So far i know that there's 3 components: Frequency, wavelength and Amplitude. Now i know that Frequency is Hertz and Amplitude is volume. What is Wavelength? Is it Distance? How far the wave length is suppose to go? I know it has to do with Nano meters but just want to make sure it has something to do with distance.
Sound waves (as I'm sure you know) are variations in pressure. A single frequency has a sinewave shape:
wave_crest.gif

The frequency is the number of these waves per second. The wavelength is distance between waves. There is a relationship between the two: velocity = frequency X wavelength. As the speed of sound is (roughly) constant, if you know frequency, you can work out wavelength (and vice versa). The hight the frequency, the shorter the wavelength.

Brilliantly, if you put speed of sound / middle c into Google, it tells you the wavelength of that note is 1.3 meters.

Also just out of curiosity, how much energy/ power in terms of voltage does it take to make a very powerful soundwave that breaks concrete and crumples metal from the inside? i know it can be done but not sure about how it's actually done.
It will depend how strong the concrete is, I suppose. (Metal sounds less plausible). You would need the pressure of the wave to be equivalent to hitting it repeatedly with a sledgehammer.

(p.s. energy and power are not the same thing and neither is measured in volts.)

4. Originally Posted by Strange
hitting it repeatedly with a sledgehammer.
Or, hitting your thumb with it to create an equally large and powerful soundwave.

5. Originally Posted by Sci_Research
Hi, Was just studying soundwaves. Ok So far i know that there's 3 components: Frequency, wavelength and Amplitude. Now i know that Frequency is Hertz and Amplitude is volume. What is Wavelength? Is it Distance? How far the wave length is suppose to go? I know it has to do with Nano meters but just want to make sure it has something to do with distance.

Also just out of curiosity, how much energy/ power in terms of voltage does it take to make a very powerful soundwave that breaks concrete and crumples metal from the inside? i know it can be done but not sure about how it's actually done.
Sound waves can destroy objects, but it occurs in a slightly different fashion from that which you imagine. True, sound intensity is definitely a factor, however, if you have not seen a wine goblet shattered by the voice of a human being, you have missed the classic example!

The key is resonance, that same old thing which Nikola Tesla was intrigued by.

jocular

6. Thanks for the info guys.

Ok so if i use a frequency in the range pH, will it hit the concrete rapidly enough (in terms of wavelength) that it will mimick a sledgehammer hitting it? Or they didn't find that out yet? Also, is the impact of the sledgehammer going to be equivalent to that of the frequency and wavelength applied if it was to be amplified?

7. Originally Posted by Sci_Research
Ok so if i use a frequency in the range pH
What is "pH"?

will it hit the concrete rapidly enough ...
Who knows. Ocean waves can destroy things. But that has a lot more mass behind it. It seems implausible that an audio wave could. I think the amount of energy you would require would basically be an explosion. If you want to count that as a "sound wave" ... meh

Unless it were a really tiny piece of concrete. After all ultrasound can be used for breaking up things like kidney stones.

There has been some research on sound as a weapon. Mainly aimed at people rather than structures. It hasn't really gone anywhere as far as I know: Sonic weapon - Wikipedia, the free encyclopedia

8. Originally Posted by Strange

What is "pH"?
pH is pica/pico hertz. It is the range used for x- Rays and Gamma Rays. It's wavelength hits very rapidly. Think of it like this:

mega-h is like this _____________ _______________ where one ______________ is one wavelength. While pica- H is more down the track past radio Astronomy, satellite communications and Infra red, pica/pico - H is more like ----------------- where one - is one wavelength.

Who knows. Ocean waves can destroy things. But that has a lot more mass behind it. It seems implausible that an audio wave could. I think the amount of energy you would require would basically be an explosion. If you want to count that as a "sound wave" ... meh

Unless it were a really tiny piece of concrete. After all ultrasound can be used for breaking up things like kidney stones.

There has been some research on sound as a weapon. Mainly aimed at people rather than structures. It hasn't really gone anywhere as far as I know: Sonic weapon - Wikipedia, the free encyclopedia
Resonance is the key or another word to describe it would be is vibration. When an opera singer sings a high note the wine glass breaks. The Frequency used by the opera singer is amplified by the echoes created in a small space in the opera theatre. Therefore i believe that with the right frequency and amplification, concrete will break due to intense heat being applied and the concrete being dried up.

I think i'll have to go hardcore in the amplification part to achieve this I'm just abit worried that the amplifier/ speakers its coming out of might get destroyed in the process.

9. Originally Posted by Sci_Research
pH is pica/pico hertz. It is the range used for x- Rays and Gamma Rays.
x-rays and gamma rays would be in the Gigahertz (GHz) range; i.e. 1,000,000,000 cycles per second. I doubt it is possible to create sound at that frequency.

Picohertz (pHz - note the z) would be 0.000000000001 cycles per second; i.e. 1 cycle every 32,000 years.

Resonance is the key
I'm not sure a concrete structure would resonate. Tap it: does it ring (like a glass)? I doubt it.

10. [QUOTE=Strange;393533]

x-rays and gamma rays would be in the Gigahertz (GHz) range; i.e. 1,000,000,000 cycles per second. I doubt it is possible to create sound at that frequency.

Picohertz (pHz - note the z) would be 0.000000000001 cycles per second; i.e. 1 cycle every 32,000 years. [QUOTE]

trust me, X ray and Gamma are in the phz range. Infrared and Radio Astronomy is in the Thz range which is past Ghz.

I'm not sure a concrete structure would resonate. Tap it: does it ring (like a glass)? I doubt it.
Not so. While concrete may not vibrate like glass does, it does vibrate as the concrete is hit by constant extreme vibration (e.g. earthquakes). Other things that affect it is the dryness on concrete caused by heat because of the frequency rapidly hitting it, which aids the vibration in destroying the concrete. That and also the amplification of the frequency.

I'll have to go hardcore on the amplification. The output might destroy the amplifier with the right frequency and amplification.

11.

12. Originally Posted by Sci_Research
trust me
I imagine these are the last words a lot of people hear.

13. Originally Posted by Sci_Research
Not so. While concrete may not vibrate like glass does, it does vibrate as the concrete is hit by constant extreme vibration (e.g. earthquakes). Other things that affect it is the dryness on concrete caused by heat because of the frequency rapidly hitting it, which aids the vibration in destroying the concrete. That and also the amplification of the frequency.

I'll have to go hardcore on the amplification. The output might destroy the amplifier with the right frequency and amplification.
Resonance by itself isn't magical. It is just a convenience that can (emphasis on the "can") enable efficient coupling of energy from a source to a load. The quality of a resonance depends very much on both the composition and shape of a material. Concrete is not particularly resonant, no matter its shape. You may have noticed a dearth of musical instruments made out of concrete. You will not find a "magic" frequency that will have disproportionate effects on it. And whatever the "best" frequency might be, pHz ain't it, for structures of practical size.

14. Your right. My apologies. Gamma is indeed in the exahertz range, and phz is actually peta hertz. Thanks for the correction Dywyddyr.

15. Originally Posted by tk421
the "best" frequency might be, pHz ain't it, for structures of practical size.
that's true, but vibration on concrete still breaks it from earthquakes. Just look at this link: Top Failure of Reinforced Concrete Building, Mexico City

16. Originally Posted by Sci_Research
... and phz is actually peta hertz.
Nope. PHz (capital P) is petahertz; pHz is picohertz. Big difference. Details matter a lot in science.

17. There is an upper limit of the frequency of sound in air (and it is nowhere near PHz).

The mean free path in air at sea level is about 0.1 micron. The speed of sound is roughly 300 m/s. Then the upper limit on
sustainable sound frequencies is:

f_max = (300 m/s) / (10^-7 m) = 3*10^9 Hz = 3 GHz

Achieving that is probably impractical. There is also, obviously, an upper limit on amplitude as well (which will be frequency dependent).

18. Originally Posted by Sci_Research
Originally Posted by tk421
the "best" frequency might be, pHz ain't it, for structures of practical size.
that's true, but vibration on concrete still breaks it from earthquakes. Just look at this link: Top Failure of Reinforced Concrete Building, Mexico City
You have a problem with logic. The finite strength of concrete does not in any way imply that there is a "best" frequency for breaking it. Again, things like shape and size matter, so there isn't going to be any one frequency that automagically causes concrete to fracture.

You want to break concrete with sound waves? Then generate an earthquake. That's all your data says.

Good luck with that. Use your not-Tesla--coil to power it.

19. I might as well Lol

20. Originally Posted by Sci_Research
Not so. While concrete may not vibrate like glass does, it does vibrate as the concrete is hit by constant extreme vibration (e.g. earthquakes).
Earthquake waves are typically below 20Hz. They are not sound waves. In fact, earthquakes are eerily silent (if you are lucky enough to be in a country which builds earthquake-proof buildings you may hear the creaking of the metalwork as it bends).

Earthquakes destroy buildings in various ways, none of which appear to have anything much to do with sound or resonance. It can be stress caused by the massive movement, by liquefying the ground or very commonly starting fires.

A magnitude 4.0 earthquake is only equivalent to about 6 tons of TNT explosives, but because the Richter scale is a base-10 logarithmic scale, the amount of energy released increases quickly: A magnitude 5.0 earthquake is about 200 tons of TNT, magnitude 6.0 is 6,270 tons, 7.0 is 199,000 tons, 8.0 is 6,270,000 tons, and 9.0 is 99,000,000 tons of TNT. As you can imagine, 99 million tons of TNT is enough to destroy just about anything, and is the equivalent of about 25,000 nuclear bombs. (This is according to the Center for Earthquake Research and Information and the U.S. Geological Survey.)
HowStuffWorks "How much energy in a hurricane, a volcano, and an earthquake?"

As many buildings will survive a magnitude 6 (or larger) earthquake, it seems like you might be better off with high explosives rather than an amplifier.

edit: It looks like those figures might be a bit low, based on this table from Wikipedia:
http://en.wikipedia.org/wiki/Richter...scale#Examples
And this calculator: http://www.convertalot.com/earthquak...alculator.html

21. But let's assume you want to create a sound wave equivalent to a magnitude 6.0 earthquake. How big an amplifier will you need?

From the Wikipedia page we can see that a 6.0 earthquake is 63 TJ

From here UUSS - General Questions and Answers about Earthquakes we see that an earthquake typically lasts 10 to 30 seconds (it feels a lot longer I can tell you). So, to make life a little easier for you, we will take the upper end. That means you need 2.1 x 1012 watts (that's 2 million MW) at about 20 Hz.

For comparison, it is rumoured that Metallica played Moscow with a 1.5 MW sound system. You would need 1,400,000 of those concerts at the same time and place.

And then you need to get the electricity supply. A significant proportion of the world's total output. The world's largest generating system is the Three Gorges Dam in China. This produces a measly 22,500 MW. So you would need 92 more of those. Better start building now.

Sounds like an interesting school science project...

22. Look up infrasound.

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