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Questions tagged [acoustics]

Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. Applications of acoustics are for instance the audio and noise control industries.

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How to find the natural frequency of a Euler Bernoulli beam subjected to unit force at the middle using impedance approach? [on hold]

I want to find the natural frequency of a beam subjected to some unit force at middle. How to do this using impedance approach?
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How does a temperature change affect the pitch of the fundamental frequency produced by vibrating string? [duplicate]

The vibrating string is tightened using tuning keys of the guitar. Assuming the amount of tightening is constant, what will change in string (mass? tension? linear density?) when a temperature change ...
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Equation for Speed of Sound [closed]

Is there a simplified equation for sound/acoustic energy that does not involve integrals? If so, does it equate with the equation in this video https://www.youtube.com/watch?v=jWobrss_8sk ?
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Is there a quasi-particle corresponding to sound wave in air medium? [duplicate]

I have seen many quasi-particle here in this list. Is there any quasi-particle concept for sound wave in air medium? If it exists, what's the purpose and usefulness of it? If it does not exist, is ...
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3answers
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A doubt related to Sound [closed]

According to laws of conservation of energy energy can neither be created nor be destroyed. We all know that sound is energy. But according to law of conservation of energy- sound can neither be ...
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2answers
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Musical Instrument that Exhibits Spherical Harmonics

A guitar string exhibits standing wave patterns when its struck, some superposition of sines and cosines, a drum head exhibits a superposition of Bessel functions when its struck. Is there any ...
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Effect(s) of different species in shock waves

In air, transitioning from a local mach number ($M$) of $M > 1$ to $M < 1$ produces a shock. But $M$ is defined simply based on the velocity of an object relative to the local speed of sound. If ...
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2answers
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How do silent kettles work? [closed]

I just had to buy a new (electric jug) kettle, and as I was bugged by the loud noise the old one made I was please to see that one can now buy silent ones. At first the new one made just the same ...
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1answer
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Why are there only odd numbered harmonics in one closed end resonant tube?

Why do we only have odd numbered harmonics at one-end closed tubes, however, if we do a frequency spectrum we have some periodic spikes between the odd harmonic spikes, just like the picture below ...
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What is the speed of sound in an artificial atmosphere?

If we could build an artificial atmosphere on Mars like in the ISS, will the air pressure be lower and the oxygen content higher? If the pressure would be lower, would people speak faster as it ...
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2answers
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Is thermal conductivity correlated with speed of sound in metals?

Right off the bat I should say: thermal conductivity and electrical conductivity are definitely correlated in metals. image source: https://www.doitpoms.ac.uk/tlplib/thermal_electrical/printall.php ...
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1answer
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Global destructive Interference and conservation of energy

As an engineer I see it like this. Imagine I send a wave and then I send another wave in phase shift to cancel that wave. Unless I am sending the wave from exactly the same point in both instances, ...
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Is acoustic levitation possible with speakers?

I read that many acoustic levitation systems use ultrasonic transducers. I am thinking of making my own drivers for speakers and running them at ultrasound frequencies. Will this be able to achieve ...
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2answers
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What is a correct loudspeaker connecting scheme and why? [closed]

Thinking of "what would be best shape for a subwoofer box?" i came to idea of a barrel, with its sides (or covers) "replaced" with speakers: I have stereo bass amplifier which is fed from single ...
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When does a closed tube with purely supersonic flow experience shocks?

If you have a cylindrical tube with all the gas moving at a mach number of exactly $M = 2$, will there be any shocks experienced? (In this case, the velocity may change, but the pressure would also ...
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Why do I hear street noise more clear on the higher levels?

I realized I'm experiencing a situation that doesn't make any sense to me at all. Back at home, my room is on the top floor of our apartment building. There is a daily music playing fountain nearby ...
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Standing waves on a guitar

If we play different strings we get different frequencies as the densities of the strings are different. This is described by: $$kL=n\pi$$ where $n$ is an integer, $k$ the wavenumber and $L$ the ...
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Pitch change opening thermos flask

If I return to my (closed) thermos flask for some more coffee, I hear a ringing sound as I open the flask (it is all metal), but the pitch of the ring increases as the sound fades - duration on the ...
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2answers
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Physical reasoning behind hearing a single shock

When an object is flying in the air at a mach number ($M$) greater than 1, a shock wave is continuously produced and the mach cone makes a particular angle, $\theta_M$, with the ground (or normal). An ...
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1answer
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High School Acoustics Experiment

Is there a way to measure the sound intensity of the sound produced from a speaker without using the sound level meter? I just am curious how we can maybe measure such intensities of sound without ...
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1answer
25 views

Can light be used as a medium to propagate sound waves on?

My understanding of why sound cannot travel through space is because sound waves are a disruption wave that require a medium to traverse on, therefore sound can only go as far as the medium it's on ...
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0answers
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can the amount of air in a pipe be calculated by the frequency spectrum it produces?

I'm interested to know if there is a way to measure the volume of air that flows through a pipe per unit time just by listening to it. I know that ideally, I can calculate the resonance frequency from ...
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2answers
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Is there a link between nuclear radiation and sound? [closed]

I'd like to understand if it's possible to relate/imagine a link or relationship between nuclear radiation and sound. A simple description would be appreciated since I don't have a deep understanding ...
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1answer
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Acoustics: Construction of the pressure field with transmitted and reflected plane waves

So I have been reading one of the papers about wave manipulation, which takes advantage of the phase shifted reflection by tailoring the design of the system. The design has two domains: air and foam (...
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3answers
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How do sound waves from different distances not mess up the pitch?

This might be a too begginer question for this site, but, if two sounds are produced with same pitch from different places, why do they sound like the same? Why do they "sync" their vallies and peaks ...
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1answer
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Shock waves at $M = 1$ and $M > 1$

When a wave moves faster than the local speed of sound ($c_s$) in a fluid, there is a shock wave since the fluid is unable to respond to the moving wave. Even if velocity ($v$) is constant, if ...
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6answers
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What does it mean to make a sound twice as loud? [duplicate]

Giancoli Textbook question: To make a given sound twice as loud, how should a musician change the intensity of the sound? The given answer is: "Increase the intensity by a factor of 10." I don't ...
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Sound barrier under water [duplicate]

Theoretically, if I were to launch something faster than the speed of sound in water (around 5 times that of air), what would happen? And if I did do that wouldn't the vessel or what ever just rip ...
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If two sound waves that are different frequencies create beats that occur several hundred times per second, can you hear this effect as its own tone?

If you have multiple waves of different frequencies, the interference from the different waves cause "beats". (Animation from https://en.wikipedia.org/wiki/Group_velocity) Let's say that a green dot ...
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1answer
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What physical property can has the greatest average effect to anticipate the transmission speed of a substance?

Rubber is often regarded as having one of the slowest transmission speeds while aluminum and steel have some of the highest. Density alone can't account for this as air is less dense than rubber but ...
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1answer
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Why does acoustic imepdance increase when mass density and bulk modulus increaes?

If we take some material and (somehow) increase its mass density or bulk modulus then its acoustic impedance will increase as $z = \sqrt{\rho \kappa}$. That is, it What is the physical reasoning ...
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What values or equations do I look up to find the energy dissipated of a sound wave through a specific material?

Generally when a sound passes through a massive object, many of the higher frequencies get cut off and the volume of the sound that passes through has been partially dampened. I'm sure the magnitude ...
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How can scattering attenuation eliminate flux in lossless media?

In lossless media (like elastic materials or non-conductive dielectrics) one can set up scattering problems involving inclusions of heterogeneous impedance as in Mie and Rayleigh scattering. Somehow, ...
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Striations in Kundt's tube

Is there some modern calculation of the distances of the striations appearing when experimenting in a tube of Kundt with different powders (sand, cork, etc) sound frequencies and amplitudes? ...
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1answer
34 views

Acousto-optical modulator (AOM)

Suppose the RF frequency of the driver of an AOM is 40 MHz. I understand that it will Doppler shift the diffracted first order beam by 40 MHz but how does it modulate the amplitude of that first order ...
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Using convolution to simulate acoustic dispersion in shallow water

Background I'm a marine biologist who's trying to wrap my head around shallow water propagation. I'm interested in how acoustic dispersion (as described by Pekeris' waveguide) alters how sounds ...
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What is the suitable form of plane wave expansion?

This question is in Acoustics area. Consider we have a common progressive monochromatic plane wave which is going in an ideal fluid toward an object. The point is that object has symmetry in terms of ...
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Surface acoustic wave devices, is this a resonance effect or forced oscillation?

I have been thinking about SAW devices the the way the inter-digital transducers (IDTs) launch acoustic surface waves. But I am unclear whether this is a resonance effect or forced oscillations. As ...
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4answers
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How are overtones produced by plucking a string?

I read the following from wikipedia: When a string is plucked normally, the ear tends to hear the fundamental frequency most prominently, but the overall sound is also colored by the presence ...
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1answer
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Subwoofer Efficiency Ratings have Inverse Effects in Small Enclosures?

I found this article on the internet which claims that higher sensitivity subwoofers have lower output in smaller boxes. http://stereointegrity.com/wp-content/uploads/Efficiency.pdf Is this true or ...
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1answer
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Noise level x amount of meters away from an outdoor singer: sphere or semi-sphere?

When computing the noise level x amount of meters away from a singer who is singing outdoors, should one rely on the standard formula $I=\frac{P}{4πr^2}$ (and then convert 'I' into decibels) or ...
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2answers
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Do whales in ocean use hyperbolic geometry to communicate? [closed]

Since the speed of sound increases with depth in an ocean, the shortest time for the sound to travel between points $A$ and $B$ may be a curved path. But does sound actually take this curved path ? I ...
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2answers
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Speed of sound in a gas and speed of a typical gas molecule

Why is speed of sound in a gas less than the average velocity of the gas molecules? Is there an intuitive way to explain this?
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1answer
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Closed End Waves [closed]

Why is phase difference between P and Q =0?
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1answer
50 views

Difference between speed of sound into a star

I try to understand the following graphics with x-axis being the radius of a typical star : I would like to knwo if $\delta c/c$ represents the relative error between theorical and experimental ...
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2answers
68 views

What is the difference between natural, fundamental, resonant, and forced frequencies?

I'm just overall slightly confused on their exact definitions, as they get thrown around a lot.
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0answers
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Bleding in convolution reverb

Since I use crystallography a lot in my studies I know that, when light or X-rays are considered many error and abberations add up to a total by the means of mathematical convolutions. So in order to ...
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4answers
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Does sound bounce in all directions, or as a ray, like light?

When light is shined on a perfectly smooth surface it reflects from it as a ray, going in only one direction. However, from my reading of Rayleigh's Theory of Sound he describes sound waves as ...
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2answers
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Is a flame whistle, pipe organ or flute possible?

Could one arrange a simple candle or wick oil lamp in a way that it would make a sound while it is burning? A simple device without a Sterling engine etc. Does the rising hot air have enough energy ...
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1answer
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When a pen is thrown on the ground, why doesn't the whole pen seem to be vibrating even though it makes a sound?

Is that because the vibration is reflected back by the boundaries of the pen, a standing wave is produced, and the nodes are so close and so numerous that it seems like the pen is not vibrating at all?...