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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Why doesnt steady flow of air create sound? [closed]

When one exhales air by twisting the lips appropiately , one does not create enough sound . But when the same amount of air with the same pressure is blown in a flute or whistle , a relatively audible ...
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99 views

Normal Modes for Standing Waves in 1-D Acoustic Ducts with Arbitrary (but real) Impedance Jumps

Let's say we have a 1-D duct, such as this: Where $Z_i \equiv \frac{P}{US}$ is the acoustic impedance, L is the length of the duct in question, and S is the area of the cross-section. In general, ...
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50 views

group velocity of acoustic waves

One can find the sound speed for the acoustic waves as follows: $\frac{\partial p}{\partial t} = -\nabla \cdot \rho \vec v$ (1) $\rho (\frac{\partial \vec v}{\partial t} + (v \cdot \nabla)\vec v)= ...
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Can you simulate a Michelson-Morley experiment with sound?

Is it possible to make a MME with sound waves? Suppose we travel on a rail platform with two "mirrors" that reflect sound, what parameters would we need to simulate the light experiment? would it work ...
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68 views

Why is root mean square pressure used in the definition of sound pressure level?

I dont understand the way we measure loudness. I know that it is in some way related to the magnitude of pressure variations. please help me figure out where my understanding fails. Let $p(t)$ be the ...
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120 views

What would the “physics” of this theoretical instrument be?

Note: I've asked questions about acoustics before in the Music Stack Exchange, but I was told it would be a better fit here. I've invented a theoretical instrument in which you have a tube that you ...
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24 views

Is the range of frequency we hear dependent on the natural frequency of our ear?

Is the range of frequency we hear dependent on the natural frequency of our ear? (i guess the question is clear enough. Just writing to meet "quality standards".)
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12 views

Averaging SPL from multiple sources, arithmetic mean or averaging decibels method?

I have measured SPL in dB(C) at several sources across a county. I am trying to model the propagation of sound from these sources and plan to use a general average of source sound using my source ...
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29 views

Non-Audio Microphone

Sound is simply vibrations travelling through the air. Would it be theoretically possible to listen to sounds through some other mechanism like infra-red or some fancy form of imaging?
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35 views

Relation between the direction of propogation of sound and loudspeaker's diameter

Sound waves from a conical loudspeaker spread nearly uniformly in all directions if the wavelength of the sound is much larger than the diameter of the loudspeaker. Sound is essentially ...
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47 views

Why do the tones differ when tapping on a different part of a coffee cup?

Let's say we have a coffee cup as shown below. The cup is, in contrast to what's shown on the image, empty (I had some trouble finding free good-quality top-view coffee cup images). When we tap on ...
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Would you hear a gravitational wave, if its amplitude and frequency were suitable?

If there was a source of a continuous gravitational wave at (say) 50hz, and amplitude of say a micrometer (a typical sound wave displacement, I think), and you were nearby (standing happily on a ...
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Gravitational waves parallel

Just an idea to illustrate the gravitational waves. This kind of analogy is proposed: When you have a rotational motion of the fluid, some small amount of the energy is radiated as a pressure ...
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Why is sound reflected and not transmitted through a wall?

We know that speed of sound is higher in a denser medium. So when a sound wave strikes a wall, why does it echo instead of passing through it with a speed faster than the speed of sound in air?
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50 views

What is the nature of ocean waves in DEEP water? [closed]

My book says that it's both longitudinal and transverse, if yes then how?
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1answer
47 views

Best frequency for Underwater Transmission

What is the best frequency of transmission of under the water for communication with good data rate? I have read that the threshold of hearing underwater is around 170 to 180 db. Can this be useful in ...
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1answer
155 views

Producing an audible sound from the gravitational waves of the GW150914 event

As is said in the latest LIGO press realease, the detected gravitational waves vary with a frequency that is audible for us. The audio one can obtain from the detected data is actually plaied during ...
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1answer
18 views

Simulating open water acoustics in a tube

For the purpose of testing an underwater acoustic transmission it is possible to use a tube filled with water with a transducer at one end and a hydrophone at the other. The problem is that sound will ...
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30 views

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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41 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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61 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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98 views

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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16 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
45 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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1answer
51 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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192 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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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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1answer
59 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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94 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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29 views

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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1answer
90 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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77 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
36 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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103 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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158 views

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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135 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
30 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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163 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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39 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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1answer
52 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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62 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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43 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
86 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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1answer
137 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
27 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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0answers
21 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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487 views

Can we see sound with our eyes? [closed]

Is there a type of sound within our visual spectrum that we can see with our eyes?
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35 views

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?