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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Is there any way a longitudinal wave can have a shear velocity component?

I am simulating the propagation of an acoustic field through elastic media. I have identified a pocket of shear stress which is travelling with a speed very close to that of the longitudinal wave ...
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129 views

To what degree does guitar construction affects the vibration of the strings?

There's an old debate going on in the guitar community about how much does wood choice and body shape affect the sound of an electric guitar. No one denies that there's a difference acoustically (how ...
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Difficulty implementing equation describing angular response of fibre-optic hydrophone

I am attempting to implement an equation in a paper which provides an approximation of the angular response of a simple fibre optic hydrophone. The equation in question (number 19) is repeated here ...
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106 views

Nonsensical dispersion relations for elastic wave propagation

In an earlier question about Einstein notation, a link was provided to a medical paper which used acoustic propagation to noninvasively detect the orientation of muscle fibers. In short, muscle fibers ...
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100 views

Sound - for purposes of vibration

What is the best way to distribute noise from more than one source (I'm envisioning a system with many), within a dome, with the ground as its primary target, at optimal frequencies and volumes to ...
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57 views

Why does the echo of the last chord appear to rise in pitch

I - and others - observe that when a musical performance ends, the echo of the last chord appears to rise in pitch by up to a quarter tone while the echo decays. This effect appears to be independent ...
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22 views

Sonoluminescence spectrum

During cavitation created by sound in a liquid the collapse of the bubbles can lead to very high temperatures and pressures resulting in the emission of light - sonoluminescence. Can the spectrum of ...
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70 views

Proof of equivalence between soundwaves and phonons in large wavelength limit (Ashcroft-Mermin, ch. 22)

In chapter 22, Ashcrof and Mermin argue that the normal modes of a harmonic crystal are not only formal but precisely equal to the large wavelength limit of acoustic phonons (which sounds, of course, ...
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34 views

Ray tracing a three-way intersection

I've been studying ray tracing in media with linear velocity-depth functions. One of the key concepts I've come across is the ray parameter, and in particular the idea that the ray parameter is ...
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298 views

What is the physical meaning of complex eigenvalues?

I understand the mathematical origin of complex eigenvalues, and that complex eigenvalues come in pairs. But what is the meaning of the imaginary part? In particular I refer to an acoustic problem ...
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64 views

Reference for the reflexion of sound in connection with boundary conditions of the wave equation

In 3D, the homogenous wave equation $$ -\Delta_x u(x,t) + \frac{1}{c^2} \frac{\partial^2 u}{\partial t^2} (x,t) \ = \ 0 \ \ \mathrm{in} \ \Omega \times (0, \infty) $$ can approximately describe ...
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54 views

What is the longest distance over which echolocation is effective?

Some animals, most notably bats, use echolocation in order to navigate and detect the location and size of objects and prey. This usually takes place over short distances. What are the theoretical ...
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44 views

Is it possible to estimate the number of people in a room from a limited number of simultaneously recorded audio samples?

Note: I struggled to decide the appropriate site for this question, between http://physics.stackexchange.com/, http://avp.stackexchange.com/, http://math.stackexchange.com/, and even ...
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57 views

Harmonics of an infinite cylinder

If a hypothetical cylinder was infinitely long, could it vibrate at any frequency, since any frequency would be a harmonic of it? And (less hypothetically) if a cylinder was only really long, would it ...
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169 views

Physical difference between two different attenuation coefficient functions

The attenuation of a wave through a medium can be modeled by the Beer-Lambert Law using an attenuation coefficient. If $I$ is the intensity, and $I_r$ is a reference intensity, then what is the ...
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98 views

Can we compute the magnitude of the stress caused by sound waves on a wall?

As a follow up to this question, Could we really compute the magnitude of the stress caused by sound waves on a wall? If so, How do we do that?
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23 views

Can I measure distance with sound through soil?

Can you measure distance (cca. with precision 0.1m-1m) with sound through soil. I know this is really crazy think to do, but I have this idea quite for a while. Basically I will set speakers on fix ...
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113 views

Resource on history of acoustics

Shortly: I am looking for a good resource (article, book, chapter in a book, introduction in an article...) about history of acoustics, I will be glad for any recommendations. By acoustics I mean the ...
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49 views

Reason behind “marble dropping sound” from concrete

Many people have experienced strange sounds from the ceiling of their home that sounds like marble dropping, often at night when they're trying to sleep. Currently there doesn't seem to have a fixed ...
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47 views

What does a long strip of explosive sound like when detonated?

By long, I mean something like (say) 2 km of detcord. Or perhaps multiple close spaced charges in a line over that distance, simultaneously detonated. Close up a single piece of explosive produces a ...
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68 views

Rayleigh criterion for sound and parabolic microphone

Currently I am developing a parabolic microphone for a study project. I've heard and read that the maximum wavelength of sound that the given diameter microphone can focus is determined based on the ...
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102 views

Bell vs. diaphragm of stethoscope for low frequency sounds

Why is the bell of the stethoscope used to hear lower frequencies if it has a smaller diameter than the diaphragm? I would have thought that a bigger diameter diaphragm could pick up lower frequency ...
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31 views

Can anyone provide a good exposition on acoustic impedance?

Can anyone provide a good exposition on acoustic impedance? Does anyone know of a good paper or textbook that does so? It seems like most sources kind of just start using it without deriving any ...
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80 views

Frequency dependance of sound wave reflection

Why are high frequencies reflected more than low frequencies off an 'acoustically hard' surface such as concrete? I basically understand that the amount of reflection is determined by the impedance ...
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29 views

Distribution of refractive index of water when applied pressure wave

I was wondering when applying pressure wave, ultrasonic sound waves, under water, how I would be able to measure the distribution of the refractive index.
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47 views

Functional relationship of pressure and position(1d)

so today I started doing my research on oscillations in a course on advanced mechanics. The experiment was to mathematically model the speed of sound in air and experimentally prove the usability of ...
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108 views

What is the physical explanation for the phase relationship between acoustic pressure and particle velocity in plane and spherical waves?

I've been looking around for a decent physical explanation of the differences in the phase relationships between acoustic pressure and particle velocity in different types of waves. Mathematical ...
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Audio anomaly identification

I left an audio recorder in the forest in many different locations for fauna identification. I am collecting subjects on my audio recorder that are clearly not in the frequency range of any animal ...
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120 views

Number of wave modes in a cavity

I'm trying to calculate the number of acoustic modes that can exist in a room in a certain range of frequencies. I thought of using the Rayleigh-Jeans formula for the electromagnetic standing wave ...
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100 views

Why do the chargers produce persistent high pitch sound?

I have noticed that my Nexus Orb charger and a charger for the shaver produce some unpleasant high pitch sounds - near the fork. Why are they doing this? Does it indicate any problem with my ...
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174 views

Harmonic frequencies of electric guitar are detuned. What could be the cause?

I have tried to record some music with my electric guitar and while playing around and looking the frequencies of single strings I noticed something strange. I took the spectra of the A string and I ...
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94 views

What is the magnitude of the sound that a Helmholtz Resonator attenuates?

I know that the shape of the Helmholtz Resonator, specifically its neck shape and the volume of its cavity, determine the resonance frequency of the resonator. Moreover, the resonance frequency is ...
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74 views

Sound localization using cross-correlation

I am using cross correlation for sound localization. I have a four microphone array (arranged linearly). My problem is, sometimes the time diff found by cross correlation between a given pair of mics ...
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64 views

Sound Intensity Measurements convert to Sound Power

If you need to have Sound Power results and the location that the microphone needs to be to make the measurement(per the standard) is not accessible. There is a machine part in between the ...
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56 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
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57 views

Design and use of the RLC model for signal processing systems and spatial acoustics

Given a frequency response for a signal processing device, set of devices, or physical space it is possible to construct an equivalent (identical frequency response) series RLC circuit. 1) Does this ...
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80 views

Energy distribution between long- and shearwaves after refraction of sound

From this explanation, I learn that sound is refracted according to Snell's Law upon passing a border between materials of different sound speed. I also learn that upon passing the border, a mode ...
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159 views

Eigen modes in a room

In a rectangular room 10*8*5 how can the eigen modes belonging to octave and third octave bands centered at 50Hz be found ? I have the formula to calculate the number of modes but don't have the idea ...
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105 views

Visualise the sound intensity

I'm studying Biophysics and my current subject is sound. One of the properties of sound is intensity. From my notes I can see the following definition: Intensity Formula is: $(I = w*m^{-2})$ or $(I = ...
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241 views

Sound Produced due to motion of air inside a tube

I'm trying to understand the sound produced by Air motion inside the respiratory system. If you have a long tube with a suction apparatus at one end , You turn on the apparatus and the air is sucked ...
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26 views

Which is has the highest (greatest) sound intensity - Sine, Square or Sawtooth waveform?

From this, http://electronics.stackexchange.com/questions/42904/square-wave-sine-wave-is-more-audible I now understand that a Square soundwave will be perceived louder than that of a Sine sound wave ...
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14 views

How to assess the acoustic power gain of resonnators (openended waveguides and Helmholtz)

I'm looking for a way to link acoustic power gain and time delay to geometries for these kind of resonnators. The botttom idea would be to design and 3d print an acoustic guitar that does not rely on ...
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65 views

At what altitude would the air be too thin to carry a sound wave?

A related question When does an aerobraking space craft create a sonic boom? has spawned a couple of answers, but so far no compelling answers. It is a common belief that in space there is no ...
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25 views

Acoustic sound box simulator

I'm looking for a simulator (2 or 3 dimensional + time) of an acoustic box. I'm trying to see where the high/low pressure areas would be depending on where I tap the box on the outside. PS. Not sure ...
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61 views

Why do I hear a squeak in my pipes when my neighbour runs his water?

I just installed a new water-heater in my apartment. Now, I hear a distinct squeak from some rooms some times when I or some neighbour run the water. Could not hear this before, and the pipes are all ...
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8 views

What's the maximum pressure from an airborne ultrasound transducer?

I'm looking at haptic feedback as an area of research. It's cool because you can "hold" a strawberry or feel a virtual worm crawling on your hand. Here's a video demonstration. ...
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14 views

Efficiency of a resonant piezo-electric transducer in air

Anyone have ballpark figures for the typical efficiency of piezo transducers in air at low ultrasonic frequencies eg 100kHz? I'm looking for energy in versus sonic energy out.
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20 views

speed of sound and ultrasound machine

How can you determine the speed of sound of a liquid using a medical ultrasound probe? I am unable to get a hold of a hydrophone. Is it possible to determine C using a or m mode?
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Does a sonic pulse in a gas enhance thermal mixing?

I have a sonic pulse consisting of around 10 cycles that is propagated longitudinally through a gas in a tube. If there are thermal differentials in the gas (say between case and central portion of ...
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Evolution of normal of material surface moving at a steady velocity

I need some help with the following question: A material surface moves with the fluid with a steady velocity $\mathbf{U_{o}}$. Show that the unit normal $\mathbf{n}$ to the surface evolves according ...