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Yes it can be done, and indeed it's a well established technology called active noise control. The idea is based on destructive interference. If at some point two sound waves have the same intensity and frequency and they're 180º out of phase then they will sum to zero and the sound intensity at that point will be zero. Your phrase negative sound just means ...

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The answer is the two are very close, but there are theoretical differences. It is VERY hard to construct actual scenarios where linear acoustic diffraction differs substantially from the diffraction of light. As noted already, linear acoustic waves are scalar pressure fields, whereas electromagnetism is a vector phenomenon, i.e. there is a polarisation ...

0

When sound waves diffract through a single slit, do they produce an interference pattern which is mathematically identical to that of light waves ...? The answer is no. The diffraction pattern of sound and of light behind a slit is not similar and so the mathematical description is not complete. This is because the real patterns on an observation screen ...

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When sound waves diffract through a single slit, do they produce an interference pattern which is mathematically identical to that of light waves in the corresponding experiment? I think the answer is almost, but not quite. It's a little complicated. First off, there's the question of whether you're talking about the far field (Fraunhofer diffraction) ...

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If you can ignore the effects of sounds attenuation in air, I believe the answer is "yes". Note that when the slits are electrically conducting at the frequency of interest for the electromagnetic case, then certain effects relating to polarization come into play as explained in Ben Crowell's answer, and the sound and light cases become more and more ...

1

Bulk acoustic waves - like the one in the quartz piezo-electric in watches or on computer chips are typically launched perpendicular to the surface by a bulk transducer. More generally, however, In a material with one or more parallel, flat surfaces, the modes of the system can all be classified by their frequencies $\omega$ and in plane two-component ...

1

The Rayleigh waves in question are a kind of evanescent wave. At least this is what happens in a surface acoustic wave filter - a neat device that converts electrical signals into acoustic ones and then back again by the piezo-electric effect, allowing the designer the exploit the low acoustic velocity to realise complex filter responses from the wave ...

2

Typically it is the ferrite cores in inductors/transformers that resonate mechanically, or through magnetostrictive effects that produce a high pitched whine. Switching PSUs are the main culprit. It can also occur when the EM fields interact with steel components in the PSU.

0

To convert one voltage to a higher voltage one often uses a transformer or a ladder network (or a combination of these). The above from Wikipedia shows a Cockroft-Walton multiplier - commonly used to step up an alternating waveform. It acts like a bucket brigade - the charge on each capacitor is being passed on to the next capacitor, at a higher voltage, ...

2

The shock wave from a supersonic object is a cone composed of overlapping spherical wavefronts. As individual wavefronts form, they propagates radially outward at speed $c$ (speed of sound) and have a radius $ct$. At the same time the object traveling at speed $v$ moves forward $vt$. The angle of the vertex of the of the shock wave is known as the Mach angle ...

1

Floris, great answer. The confusion in the question is a really common one that isn't emphasized enough in teaching. Intuitive View Here's an easy way to remember this: When the speaker pushes, the air touching the speaker moves one way. When the speaker pulls, the air touching the speaker moves the other way. Put more formally, for each movement of the ...

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The only place where I have ever seen this done successfully, and actually heard the cancellation was in a room where there were no reflections from the walls or the floor (an anechoic chamber). In this case, the cancellation was so perfect that I couldn't hear anything. I took a couple steps laterally and then the sound returned. I was quite stunned. I ...

2

Here are some topics to read about: Frequency doubling, also called second-harmonic generation as Johannes mentions. Here, you put one wave into a medium, and some fraction of it is converted to a wave with a different frequency. By carefully engineering the medium you can get quite a high conversion percentage. Other nonlinear optical processes, not just ...

1

Although normally considered as photon interactions, any inelastic scattering process will result in the alteration of the frequency of the electromagnetic radiation. An obvious example is Compton scattering, where high energy (X-rays+) light scatters from free electrons. The scattered light has lower energy and longer wavelengths than the light incident ...

4

According to the MTU webpage Speed of Sound in Air, some things to consider: if the ideal gas model is a good model for a real gas, then you can expect, for any specific gas, that there will be no pressure dependence for the speed of sound. This is because as you change the pressure of the gas, you will also change its density by the same factor. ...

4

The nonlinear term, $\left( \mathbf{V} \cdot \nabla \right) \mathbf{V}$, determines the steepening of a wave. This can be balanced/offset by loss terms like dispersion, diffusion, viscosity, resistivity, friction, etc. If the loss term dominates over the nonlinear term, then the wave cannot steepen as there is too much damping. If the loss term balances ...

1

The actual shock wave is quite short lived (I think it's visible for less than a second near 0:14 as a white sheet around the smoke/dust cloud) and doesn't propagate very far in this case. When the shock dissipates what's left is a pressure wave, the "bang" or sonic boom, and that propagates at the speed of sound. So I guess your video uses a reasonable ...

1

Intensity is defined to be the average energy passing through a unit area per second. The key here is average. By defining it this way, we avoid intensity that varies with every period. The average intensity doesn't change unless the source changes it. In calculating the intensity the r.m.s. average pressure is calculated, and this is proportional to ...

0

The phase speed of a sound wave is dependent on the wave amplitude. This is how and why a sound wave can steepen into a shock wave. In fact, without dissipation, even the sound waves produced from talking would steepen uncontrollably to a point similar to a shock, but would break before forming a shock (since dissipation is required to initiate shock ...

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Molecules in the outermost layers of the atmosphere are always reaching escape velocity - but there is sufficient statistical fluctuation that you will never, ever be able to demonstrate that your shout made a particular molecule escape. Let's do some math. Assuming that your sound wave is still a sound wave (rather than a shock wave) when it leaves your ...

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I'll just give a short outline (many caveats though): Energy in sound waves drops off as the square of the distance (a sound wave spreads out as a sphere from your mouth). If we do not take dissipation into account, you need to compare the maximum energy of your shout and divide it by $R^2$ with $R$ the distance you want to consider. Compare the kinetic ...

1

If you have a small diapragm moving slowly then the air will just flow around it and you won't get any appreciable pressure rise in front of the diaphragm. That means there won't be any longitudinal pressure waves (i.e. sound waves) generated normal to the diaphragm surface. If you now make the diaphragm larger the air has farther to move to get to the ...

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A number of factors influence the sound of a wind chime: The length of the pipe The diameter of the pipe The thickness of the pipe The material of the pipe (density, young's modulus) How the pipe is struck How the pipe is suspended These last two points are really important - when you strike exactly in the middle, you will excite the odd modes (only) of ...

1

Due to evaporation a layer of air forms between the water droplet and the hot surface which causes the system to vibrate by letting air escape in bursts and produce sound. I suggest reading about the description of the sound that was recorded in the Leidenfrost experiment. Article: http://www.nature.com/srep/2012/121010/srep00720/full/srep00720.html Video: ...

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