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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Are there materials that are opaque to infra sonic waves?

I have read that infra sonic sound waves because of their large wavelengths pass through most materials largely unabsorbed. However, are there materials that absorb infrasonic waves(could be frequency ...
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239 views

Frequency of Sound Waves

Is the frequency of the echo (resulted from the reflected sound wave) equal to the frequency of the original sound wave?
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How to arrange a 3d cymatics experiment?

Various researchers have filmed levitating polystyrene using sound waves. If i were to take 3 speakers and attempt to visualize the standing wave fields formed by the three speakers, how would i do ...
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44 views

If you play more than one music track at once on a computer, does the sound heard get louder?

Say you are using a computer and have multiple Youtube videos playing music (or any other video) at the same time, does the sound produced by the computer's speakers (or a pair of headphones) become ...
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Can sound produce electricity?

Energies of wind and water can produce electricity. But, can sound energy also be used to produce electricity?
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What state of matter is thunder? [closed]

I know of solid, liquid and gaseous states of matter but what state of matter is thunder? Is it gas, liquid or solid?
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theoretical echo from a point scatterer

How can I compute an echo coming back from a point scatterer? Let's say I know the excitation signal (plane wave), scatterer position, medium properties, what else do I need to see, how the echo will ...
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1answer
32 views

Sound insulation, absorption and diffusion. Can they be part of the same process? [closed]

I understand that insulation, absorption and diffusion in acoustics are different concepts. Notwithstanding, would it be correct to assume they may be part of the same process when all are used to ...
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37 views

How does electrical energy gets converted to sound energy?

I have seen that inside headphones there is a magnet with a coil of thin wire around it. There must be longitudinal waves coming out of it that is why we can listen to audio. There must be pressure ...
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1answer
337 views

Why can we hear sound better on the water than on land?

If we sit in a boat on a lake we can often hear people talking on the shore clearly in contrast to sitting in an empty field and hearing the people talk over the same distance. I heard that this ...
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316 views

Why does sound become louder and increase frequency if I give it a narrow path?

If I put my hand over the speaker of my phone like in the picture, I can clearly hear my music amplified, why does this happen? The only cause I can think about is the fact that all the intensity ...
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55 views

A sound that always seems to come from behind you

Many years ago I heard a radio broadcast featuring a beeping sound that always seemed to come from behind me. The announcer said that the sound would have this quality and it did, even when I turned ...
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Calculating displacement amplitude of ultrasonic power transducer

I am not a physicist, but my current project drives me to some physics-related computations, hence seeking help. I have some ultrasonic transducers, 5938D-25LBPZT, for which very limited information ...
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Why are the closed and open ends of an organ pipe nodes and anti nodes?

Here is a diagram of a wave in an organ pipe you'll find in most physics books Waves in air are longitudinal (not traversal), so what do the curves represent? Why are the open ends always anti ...
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Can Acoustic levitation be used to contain antimatter?

Can Acoustic levitation be used to contain antimatter? To me, It sounds like an obvious use of the phenomenon, but I didn't find any documentation about anyone trying this on the web, which could ...
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Did temp change affect the propagation of sound? If yes then how? [closed]

propagation of sound is affected by change in temperature. Is it increases or decreases and how?
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44 views

Why we cannot hear ourselves or speak in water

I've tried several times to shout when I'm inside the pool but have failed to make any sound. Nor am I able to hear anyone talking outside. Why does this happen? The frequency does not change and ...
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Fourier transformation in nature/natural physics?

I just came from a class on Fourier Transformations as applied to signal processing and sound. It all seems pretty abstract to me, so I was wondering if there were any physical systems that would ...
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2answers
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How is energy conserved in resonance?

According to Wikipedia, [...] resonance is a phenomenon that occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential ...
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Effective medium approaches - Volume averaging vs homogenization?

In dealing with multiphase two phase systems as an effective medium there are two approaches that can be taken. Volume averaging and homogenization. Volume averaging is very intuitive, just take ...
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Why does sound need air in order to travel?

I know that in space, because of vacuum that we can't hear voices or sound to be specific, why is that? Why does sound need a medium to go through?
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Why do we hear the square of the wave?

Assume we superpose two waves of frequencies $\omega_1, \omega_2$. Then what we get are beats. Adding the two sines gives us $$\psi = A\sin(\omega_1 t) + A\sin(\omega_2 t) = 2 \sin ...
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Can you hear vibrations through your bones?

If we have a source, like a speaker, but with no sound and only the vibrations, and this vibrations were transported to a surface which you can put your elbows on it and then put your hands to your ...
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1answer
31 views

Please help me with this doubt from waves

what is phase difference and how to visualize it? i am able to understand it pretty well in sinusoidal waves but please tell me what it is in other type of waves like plane waves,spherical waves,etc.
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How loud would a sound have to be to be heard around the world?

I'm reading the book Cosmos by Carl Sagan, and in it he states: Striking the Earth's atmosphere, a modest cometary fragment would produce a great radiant fireball and a mighty blast wave, which ...
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Influence of acceleration in acoustic doppler's effect experiment

Recently I've done an acoustic doppler's effect experiment for physics lab assignment. The setup was two microphones in a straight line, movable object with sound source and a pc with the usual sound ...
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1answer
44 views

Can sound reflect from itself?

If it is possible, what kind of conditions would be necessary? The case with electromagnetic waves could also be interesting, but I don't think that is possible.
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How do transverse sound waves (in solids) convert to longitudinal waves (in gases)?

I know that in solids sound can be a transverse wave and that in gases it is a longitudinal wave. The question is what happens at the boundry at the two substances? What is the mechanism of conversion ...
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why it is said that the mach number of noble gases should be less than 0.1 in order to avoid non linear effects?

while reading about the construction of thermoacoustic refrigeration i read that the mach number of the noble gases should be less than 0.1 to avoid non linear effects. what is the science behind ...
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Sound as a use to separate molecular structures

Sound can be a destructive force. However, could it be used to separate say the Hydrogen atom from the Oxygen atoms?
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Resultant frequency if 3 harmonic notes (a chord) is played

If I know the frequency of individual notes being played (let's assume D, F# and A), how do I determine the final frequency if they are played (nearly) simultaneously as a chord. To put the problem ...
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why stack width is larger than the thermal and viscous penetration depth in thermoacoustic refrigerator?

The thermal and viscous penetration depth is smaller than the spacing in the stack:this assumption leads to the simplification of Rott‟s functions, where the complex hyperbolic tangents can be set ...
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1answer
23 views

What is sound intensity?

In my medical physics book it says that Intensity is 1/2 a2/pc=a2/2z Where a is the amplitude, p medium of density, c velocity of that wave and offcourse Z is the impedance. When I google it it just ...
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2answers
27 views

Pin point sound wave on phonon dispersion

Imagine a sound wave of 1 Mhz is pushed into a material, in order to plot this on a phonon dispersion relation (E-K plot) - should I convert the 1 Mhz into wavelength(lambda) and find the equivalent ...
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93 views

Could sound be considered a kind of renewable energy? [closed]

Is sound energy useful as a source for generating electricity? If so, could it be a renewable resource?
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Stiffness in water

How do I find the stiffness or Fluid Elasticity for water (at a given temperature of for example 40 degrees)?
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35 views

Does a trumpet play at a tritone lower without lip vibration?

My trumpet teacher noticed that if you blow into a trumpet for warm-up, without any lip vibration, there is still a slightly audible pitch which is a tritone lower than "expected" in the following ...
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1answer
31 views

How far away must I stand to not hear sound (interference) [closed]

I`ve been trying for a while. I have two speakers with 4 meters between them with music playing on 250 Hz so the wavelength is 1.36 meters, How far away do i have to stand in front of one of the ...
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1answer
146 views

Acoustical wave equation from Hamilton's principle

It is common to show the features and power of the Hamilton's principle by deriving the equation of vibrating string, membrane etc. using this principle. But I have never seen that used for deriving ...
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1answer
60 views

How to find the first-harmonic frequency from the frequency spectrum of a recording of this harmonic being struck on a guitar?

Just as the title implies, I was trying to find the fundamental frequency of a guitar string at various tensions as a part of an experiment to find its Young's modulus. In the experiment, I connected ...
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1answer
37 views

Waves and Sound [closed]

An organ pipe of length 1.5 m is open at one end. What are the lowest two harmonic frequencies? As it is open, $V = 2lf$ $V = 343m/s$ Therefore: $343 = 2 \cdot 1.5 \cdot f$ $f = 114.33Hz$ But ...
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26 views

Resulting amplitude due to two equidistant sound sources

If sound sources have same amplitude say $A$ and nearly same angular frequency like say $\omega_1$ and $\omega_2$ then at a point equidistant from them is it correct to assume that the ...
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Expansion of Lighthill source term problem

Studying M. S. Howe's Theory of Vortex Sound I need to compare following two approximations of Lighthill's source term $L$: $$ L_1 = \mathrm{div} \hspace{2pt} (\omega \times v) $$ $$ L_2 = ...
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Why is the sound channel in the ocean especially good for low frequency sound?

Why does not the high frequency sound propagate as far? The dispersion curve $\omega(k)$ is almost linear, right?
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348 views

Can we see sound with our eyes?

Is there a type of sound within our visual spectrum that we can see with our eyes?
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A question about the sound channel in the ocean

The sound channel (SOFAR channel) in the ocean is about 1000 meters below the surface. It is said that sound can get trapped in this channel and propagates thousand kilometers without dissipation, ...
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1answer
152 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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197 views

Significance of higher harmonics

I am analyzing a noise signal and have identified the fundamental frequency of a tone and it's higher harmonics. Say for example given the signal below, The fundamental frequency has a sound ...
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4answers
124 views

Why is perceived sound intensity based on a log10 scale?

Decibels are logarithmic with a base of 10. I've been told before that two car horns are not twice as loud as one car horn. Rather, it takes ten car horns to be twice as loud, because of the log10 ...
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1answer
2k views

What arrangement of sound waves would be needed to heat air in a typical sized room?

From what I understand, sound is simply the jostling of the molecules that make up the air in a specific pattern, widely known as waves. I also know that these are longitudinal waves. If we were to ...