# Tag Info

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To go into the actual physics of the system answers become very long and answers get comments, so I would just like to add: about the organ of Corti as a highly selective frequency analyser, about inner hair cells, about the arrays of outer hair cells and how they all are embedded in the basilar membrane and looking at the places where they are embedded, ... ...

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A rather hand-waving explanation of the process of recording and reproduction is: Sound is a pressure wave, and you have a microphone which converts the pressure fluctuations into electrical signals which drive the cutter to produce the master for the vinyl disk. The cutter produces a groove where the depth corresponds to the pressure variation at the ...

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The key is not the vinyl (cause e.g. CD just have "coded electronic ups and downs"). It's a feature of recorded spectrum, i.e. the shape of ups and downs.

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Well, you ask for a "resultant sound" but, in fact, when you play a note, for example A4, not only one sound is played. In theory, a wave can be represented as a sine, a simple oscillation. For example, a wave propagating on a string can have the following form: $$y(x,t)=A\sin(2\pi ft-kx)$$ Where $f$ is the frequency of your sound (A4 = 440 Hz, for ...

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The most common approach to model the sound radiation from a vibrating body is generaly the same as in all wave cases: continuity is the key. Let's say that a sphere is vibrating (changing it's volume periodically), then the acoustic velocity of the air particles just on the boundary with the body must be the same as the velocity of the sphere surface. It ...

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May I ask what you think of as sound? If sound is the vibration of air- or in general any material agent- then sound is the sensation you get from the changes in the pressure of the air, it's what reaches your ear and then produces some signals interpreted in your brain. Sound is the vibration, not something produced by the vibration. This vibration which ...

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Take your hand and move it. By moving your air, you moving the air. This is what a vibrating object does - it moves the air. Sound is just the movement of air (or a liquid or solid).

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Sound waves can be emitted not only by vibrating bodies, but whenever there are pressure differences as the result of thermodynamical instability. Therefore even putting out the cigarette can produce sound cause of high temperature (and therefore pressure) differences. It's not an event with pronounced frequency characteristics, because the differences ...

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You correctly assumed that sound in space does not propagate ( the density of gas molecules is between 1 per cubic meter and 1 per cubic centimeter, too low to efficiently propagate sounds ). But the Camera is mechanically attached to the space suit, which contains various mechanical parts, like a thermal control system to manage the temperature inside the ...

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Well, if I'm not mistaken, it's pretty straightforward. Let $p(r, \theta, t)$ be separated in two functions with variables of time $T$ and spatial variables $\Theta$ (I'm not using $R$, cause it's already defined): $$p(r,\theta,t)=\Theta(r,\theta)T(t)$$ then: $$T = e^{i\omega t}$$ $$\Theta = i\frac{Q\rho c k}{4\pi R}e^{-ikr}$$ $T$ is given ...

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Perhaps I could share some idea for further research. If we could make actual and correct pressure measurements in the cochlea to reveal wether the non-stationary Bernoulli effect is a good description of the actual physics-of-how-the-cochlea-isolates-frequencies-along-its-length? I would consider: I would propose to use a pitot tube, with sensor in the ...

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The cochlea has a complex physical structure, with multiple membranes and fluid-filled chambers. Therefore to explain the separation of frequencies along the basilar membrane of the cochlea is complex to. Sure, there are a lot of very general descriptions (even the answer of theblackcat) and a lot never go into the actual physics of the system. This ...

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The reason D is the "correct" answer, is because the key word best, is used. Although any answer may not be 100% correct, if at least one of the answers is better than the others, then that would make it the correct answer. A and B are eliminated because the amplitude should decrease as one moves away from the XY center line. C is eliminated because it ...

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Here's an article about acoustic version of laser named SASER. http://en.wikipedia.org/wiki/Sound_amplification_by_stimulated_emission_of_radiation It can emit very directed acoustic field. As far as I know, present versions have quite limited posibilities, but if you're writing SF it may be inspirational.If SASER's wave can propagate in human body, which ...

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I tend to disagree. Acoustic levitation is based on the standing waves phenomenon and therefore it needs a bit time to be established. Emmiting a ray of sound to hit the bullet is not a good way to deviate it from its path. If I was a sci-fi engineer in the field of acoustic defense, I would create walls of standing waves with knots and antiknots organised ...

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So far the best commercial unit I've found for this is this one: http://www.enoscientific.com/well-watch-600.htm They use a 60 hz audio signal, with some signal processing to reject false returns and do edge detection. It records to a flash card, has a USB port for downloading, and optional radio access.

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One of the ways of motivating the multipole expansion is as follows: consider a system of charges (more generally, sources, but let's consider the electrostatic case in particular) $q_i$ with position vectors $\mathbf{r}_i$. We want to calculate the electrostatic potential (more generally, whatever field you are interested in) $\phi$ at a point $\mathbf{R}$, ...

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1/f spectra have the unique distinction of being "scale invariant" in the sense that the energy in an interval df is proportional to df. The 1/f spectra in fact have the property that the in an interval with width df available energy is proportional to df but not with f. There, namely "scale invariant" attribute for. It is not the energy, but the signal ...

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From the Wikipedia article on fog: Sound typically travels fastest and farthest through solids, then liquids, then gases such as our atmosphere. The distance the water molecules are from each other, and temperature, are the reasons sound is affected during a fog condition. Molecule effect: Though fog is essentially water, the molecules are barely ...

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According to this link sound (especially high frequency sound) is more attenuated in fog, because it is dispersed by the (billions of) air-water interfaces of all the droplets. This is one reason why a fog horn is a very low sound - low frequencies travel further, especially in fog. For echolocation you want to use high frequencies, and fog is more ...

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I am not sure if you mean something like this, since it is man-made but it does not include engines: The tip of a whip can move faster than the speed of sound, this is why it creates this loud noise. see http://en.wikipedia.org/wiki/Whip for some further information.

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Tsunami waves are very fast. Speed of tsunami wave in deep ocean may get higher than the speed of sound in the air: http://wcatwc.arh.noaa.gov/?page=tsunami_science

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Neutrinos passing through you. Photons from the sun. The tangential velocity of many points on the Earth. The speed of beta particles.

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For our three compartment hearing sense, from a physics point of view, there is a basilar membrane stimulation, from base to apex, in its pathway in the cochlea, to a place on the basilar membrane. By periodic movement of perilymph, non viscous fluid, backwards and forewards, in the cochlear duct meet the conditions of a potential flow. The basilar ...

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However interesting, your question is probably too broad. When it comes to perception (so not just simple objective values), this topic is actually not perfectly understood in general. Always remember, that perception of any parameter of the sound is nonlinear and dependent on other parameters (e.g. you need to consider a pitch of the tone, when you ...

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If it's suspended by a magnetic field, then ringing will cause a disturbance of the field. This will cause radiation of electro-magenetic energy. The same is also true of the gravitational force the bell exerts on it's self. The ringing will cause gravitational radiation (loss) of energy. Assuming that the bell is the size and density of a large black ...

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Anything that "suspends" the bell - whether it be a bolt, a piece of string, or a magnetic field - is applying a force. When the bell vibrates, this vibration will be transmitted. This is because the force of a magnet is a function of position - you can only get magnetic attraction because of a divergence of the field, so if you move, the force changes and ...

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