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 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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14 views

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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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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55 views

What state of matter is thunder? [on hold]

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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11 views

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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52 views

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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46 views

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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53 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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48 views

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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41 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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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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54 views

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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46 views

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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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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74 views

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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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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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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3answers
92 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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2answers
26 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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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
33 views

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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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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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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57 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
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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20 views

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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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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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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21 views

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
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Acoustical Design considerations for Active Noise Cancellation Project for Air vent [closed]

I am working on ''Active noise cancellation for air vent'' project. I am using NI myRIO1900, Audio Technica ATR 3350 omni directional microphones and Tevion Loudspeakers. I have done the programming ...
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The sound energy when two or more objects collide

When two objects collide in an inelastic collision, some kinetic energy is converted to sound energy and heat. How do I determine how much of the kinetic energy is converted to sound energy? Provided ...
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1answer
32 views

Which point is taken as origin for sound wave equations?

In sound wave problems mostly it is mentioned like there are two waves travelling in opposite directions like say $\sin (t-x)$ and $\sin (t+x)$ which produce stationary waves in a closed organ pipe ...
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3answers
509 views

Can vinyl LPs store audio above 20kHz and can it be played back? [closed]

If, in the future, humans genetically engineered themselves to be able to hear frequencies significantly above 20kHz (say, up to 100kHz), would they find vinyl LPs a viable method of storing and ...
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Why can't the human voice produce a Shepard tone?

Audio of a shepard tone on youtube. So what is a Shepard tone? A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When ...
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Why is the speed of sound lower at higher altitudes?

At sea level the speed of sound is 760mph, but at altitudes like the Concorde would fly at (55,000ft) the sound barrier is at 660mph, so 1000th slower. Does it have to do with lower pressure?
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Why does the metal mesh in an electric swatter make a whirring sound?

I have an electric bug swatter that operates on a rechargeable lead acid battery. I had one before that operated on disposable batteries and when it was turned on, it made a high pitched whining ...
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272 views

How is the perceived quality of sound measured and analyzed?

I am doing a physics experiment researching the effect of temperature inside the clarinet pipe on the quality of its sound. I know that the speed of sound is directly proportional to temperature of ...
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1answer
25 views

How to relate heat build up in an open pipe to sound frequency and specific heat capacity of the pipe's material.

I am designing a physics experiment with my clarinet. A temperature probe and a microphone graph changes in temperature and sound pressure, respectively. I am trying to demonstrate how different woods ...
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1answer
54 views

Is there really no transverse sound wave in air? [duplicate]

Everything has some viscosity. The viscosity of the medium may support transverse wave, right? So, is there really no transverse sound wave in air?
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1answer
66 views

Fractional harmonics in musical Instruments

I recently did some Fourier transforms on different audio files containing saxophone or trumpet (John Coltrane/Clifford Brown). I found that with the saxophone, the frequency spectrum occasionally ...
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1answer
19 views

Wave on a string to sound wave

If you have a string of 2m in length, and the wave speed on the string is 2m/s. and when then string vibrates at fundamental frequency the wavelength of the wave would then be 4m. However, the sound ...
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32 views

Is there sound diffraction grating? [closed]

Sound is also a wave phenomenon. Therefore, is there any counterpart of the usual optical grating for sound?
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1answer
30 views

Sound attenuation when holes size less than wavelength

The actual problem is as follows. There is a gap between a transducer and its circular mounting collar that is about half the wavelength of the incoming sound. What I do not want is for the incoming ...
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1answer
65 views

What happens to a sound wave going from air to vacuum?

Let's say you are in a space ship. The inside is filled with air, a medium in which sound waves can exist and travel. Then there's a wall, still a medium in which sound waves can exist and travel. And ...
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DIY ultrasonic cleaner - will it work? [closed]

I want to build some simple ultrasonic cleaner and I wonder: is my idea going to work? The plan is: Build a container from metal sheets or just find/buy some container. Buy something like 60W 40 kHz ...