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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Rarefaction/compression events detection using time resolved sound measurement

I had a question about sound measurement in air using a B&K condenser microphone. In the acquired time resolved sound measurement signal I can see both negative and positive voltages/ pressure ...
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59 views

When does the shock occurred?

I'm between this 2 conditions that when does the shock occurred over an airfoil. When the speed of point of an airfoil reach to sonic velocity of environment. When the speed of point of an airfoil ...
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Confusion about the shock growth

I am studying Hamilton's & Blackstock's Nonlinear Acoustics. One of the essential phenomena associated with a finite-amplitude (unidimensional, planar) sound propagation is building the shock due ...
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22 views

Pressure Inverting Reflection of a Sound Wave

How would the frequency and energy of a pressure inverted sound wave compare to the frequency and energy of the original sound? Would it sound any different?
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Sound pitch of glass with water

I have a glass (made from glass) at room temperature. I poured very hot tea in it and started stirring. No extra tea is poured in the glass. When hitting the glass with the spoon, I noticed the ...
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60 views

Helmet to helmet in vacuum - can we talk?

Usual SciFi scene. In a spacesuit, in vacuum, with the comms out for some reason. They want to talk, so the butt helmets together so sound can pass through. Questions are: a) Would it really work in ...
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Why don't we hear sound reflecting from buildings, mirrors, etcetera?

We can see buildings, doors, cars etc. as light falls on it gets reflected to us. but why doesn't the same thing happen with sound? I mean why don't we hear sound reflecting that much?
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659 views

Liquid wave faster than sound in the above gas: possibility implications

I recently heard that tsunamis (meaning "harbour wave") can travel over 800 kilometres per hour (500 mph), not so far from the speed of sound in the air. May it happen, in general, that a wave in a ...
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What would happen if we try to emanate sound waves from a conic surface? [duplicate]

Say we want to emanate sound waves through a conical surface, what would happen at the tip? How would the waves be?
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58 views

Can Doppler Shift be used to calculate speed of an observed object?

Thanks for looking. Just musing over an idea this afternoon: if I had a radio controlled plane, I could obviously calculate its airspeed based on pings and the known speed of sound if it was ...
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37 views

A question about different intensity of a sound source in a room

A few days ago, I entered a temple room with dimensions (which are only approximate) shown below in the diagram. There was a low humming sound of the exhaust fan which was at a height of approximately ...
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36 views

Standing wave confusion

To form a standing wave, two coherent waves must travel in opposite direction. But is it it necessary for them to have the same amplitude and no phase angle difference?
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107 views

Do gravitational waves travelling through a medium produce sound?

Say Alice decided to orbit dangerously close to a couple of black holes circling each other. She is in a heavily enclosed astronaut suit, as is Bob, who is floating much further away. Assuming Alice ...
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Is it possible for a harmonic to be louder than the fundamental frequency?

Using most sound equations, it is quite clear that increasing frequency decreases amplitude, but is there any example where this is not true?
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Why would a decreased length mean a higher frequency of sound?

This is in terms of the Water Bottle Lab: adding water (effectively decreasing length) to a bottle and finding its fundamental frequency at different lengths/amounts of water. I understand what ...
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52 views

When you push a stick will the end of it respond later than the beginning? Is so what is the fastest material and what forces are involved?

Normally when two people hold a long stick the receiving person would feel at the same time the stick moving when the first person gives the stick a push. But is that in reality exactly the case? ...
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21 views

If there are two different standing waves of different lengths in an open air column, what frequency would resonate?

Suppose I am playing a hypothetical woodwind instrument with both ends open. Somewhere along the length of the tube is a hole, which cannot be at or near the exact center of the tube for the sake of ...
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1answer
34 views

Speed of light and sound

Speed of light is universally constant so in denser media its collision increases so effective speed will decrease so how we distinguish this effective speed and $3\times10^8$ m/s. But why sound ...
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1answer
31 views

What determines the size of features on the CMB?

I have been learning about baryon acoustic oscillations. I am however confused about the size of the features as seen on the CMB. It is claimed that the largest structures have a size given by the ...
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4answers
51 views

About speed of sound?

Even though Speed of sound at room temperature is very large equal to 342m/s yet it does not cover that much large distance when we speak. What are the conditions at which sound really travel 342m in ...
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Dispersion Relation for Convective Wave Equation

The convective wave equation governs the propagation of sound in the presence of mean flow: $$ \frac{D^2p'}{Dt^2}-\bar{c}^2\nabla^2p'=0 $$ or, expanded out: $$ \frac{\partial^2p'}{\partial ...
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Noise created due to change in Air Pressure

Background : My blower in one of the experiments is generating noise due the a short airflow path to atmosphere. The reason is due to a sudden change in pressure (high to low) the high noise is ...
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3answers
74 views

Baryonic acoustic oscillations: Why are there standing waves in the CMB?

On page three of the following http://www.quantumfieldtheory.info/CMB.pdf, Klauber talks about the formation of standing waves from acoustic vibrations in the early universe. He claims that they form ...
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2answers
32 views

Is it possible to create sound focus in a room?

Is it possible to create a place, where sound, produces by room's environment, is loud in one or several points, but barely audible in other parts of the room?
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Why are sound waves adiabatic?

I want to know why we can treat sound waves as an adiabatic process. Precisely, I know that pressure and density vibrations occur so fast that molecules have no time to exchange energy (I might be ...
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How can you make harmonics on a string? [duplicate]

For an oscillating string that is clamped at both ends (I am thinking of a guitar string specifically) there will be a standing wave with specific nodes and anti-nodes at defined $x$ positions. I ...
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Is the velocity with which molecules of the medium oscillate same as velocity of the sound in that medium?

I wanted to know that under sound field applied molecules of the medium oscillate with some velocity in the direction of sound propagation. Is this velocity same as velocity of the sound in that ...
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29 views

Why is sound intensity defined as the product of pressure and particle velocity?

The intensity of a sound wave is defined to be $$\vec{I}=p(x,t)\vec{v}(x,t)$$ I can see that the units on either side of the equation balance, but I can't find a derivation online that shows why ...
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Is the fact that sound travels faster in metal than in water related to the fact that hitting metal is louder than hitting water?

I am mostly a mathematician but have some physics background. I was tutoring high school physics, and we were covering the speed of sound in various mediums. He noticed that the speed of sound in ...
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Book recommendations on physics of music and musical instruments [duplicate]

I am pursuing a degree in Mathematics and have a strong interest on music. I would like to understand the physical basis of how is music made. Does someone know some bibliography on this subject?
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35 views

Is the speed of sound observable without tools?

Many times, I had already had the impression that what I was hearing was desynced from what I saw. Could this be caused by the speed difference between light and sound? Or is sound still fast enough ...
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45 views

How fitting is the sound wave (transverse wave) propagation model? (for the layman)

Air is a gas, then how is sound wave propagation possible? I mean, gas particles have a tendency to travel in a straight line, so how does a sound wave occur via compression and rarefaction? Most ...
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36 views

Is it possible to generate deep infrasound with subwoofer and a pipe?

I would like to check if infrasound noise can make people feel weird (as in a "haunted" house). Some people claim that noises of such frequency may be the cause of "paranormal" sensation in humans. ...
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25 views

Sound frequency and power

Although I have studied physics I am not clear on this question: Given that two (or more) sound waves have the same amplitude does the power they carry depend on frequency? What about electrical AC ...
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Ultrasound Transducers and Simulator [closed]

Presently I am working on Underwater Acoustic Wireless Transmission. I desire to measure water parameters at the bottom of the surface of the water and then pass it to the water surface using ...
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57 views

Outdoor noise 55dB, how loud will it be (on average) 10-12 feet away?

If an outdoor air conditioner component that makes 55dB maximum noise at high speed operation, how far away would a neighbor have to be to not hear it?
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1answer
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Does air have a maximun supported sound intensity? [duplicate]

It's probably a stupid question, but I wonder what the limit of intensity is that sound can have in the air. I suppose that there's a limit, because very high pressures produced by the sound wave ...
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Standing waves and acoustic levitation

i am doing a new personnal project about acoustic levitation with standing waves into ambiant air using a piezo ultrasonic tranceiver and a reflective pannel. I modelised both of the emission and the ...
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Does the distance between tines affect sound of tuning fork?

Tuning fork handles act as clang-mode wave nodes. Therefore, I postulate that by symmetry the distance between the tines should not affect the frequency nor the volume. Let us neglect here ...
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3answers
71 views

What's happening to my metal pot that makes boiling water so noisy?

When starting a fire in a metal wood stove, you can often hear the metal "ping" slowly at first and then faster as the stove heats up. Once the stove has been running for awhile and has heated up, the ...
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2answers
57 views

Can every single sound ever made(from the beginning of time) be recreated again?

Sound is a wave and energy decreases as $1/r^2$ . The intensity of sound is proportional to $(amplitude)^2$ of the wave. So if we amplify the wave with some instrument then we can hear every single ...
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150 views

Sound Intensity and Frequency Relation

The intensity of a wave is proportional to the square of the amplitude of the AND the frequency of the wave given by the equation: Now when talking about sound waves the sound level of a noise ...
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870 views

How is a human voice unique? [closed]

Well, I am quite new to concepts of vocal sounds. From the physics point of view I believe a sound has two basic parameters i.e, frequency and amplitude. Considering the end sound wave produced by ...
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33 views

factors that affect energy of a sound wave?

Putting a lot of energy into a transverse pulse will not effect the wavelength, the frequency or the speed of the pulse. The energy imparted to a pulse will only affect the amplitude of that pulse.why ...
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1answer
54 views

Why doesn't frequency of a sound wave reduce with time?

I understand how energy depends on amplitude as this source says but this source mentions that the energy of a sound wave depends (maybe "also on") on frequency of the sound wave. If energy of a wave ...
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1answer
45 views

Effect of temperature on speed of sound [closed]

Formula for calculating speed of sound in dry air is $$V(t)=V(0)+0.61t$$ The temperature here is always taken in Celsius .Why don't we use kelvin?
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1answer
58 views

Why does wind sound the way it does?

You can obviously hear wind. From everyday experience, the stronger the wind, the louder its sound. But this sound is always similar, and quite distinctive, noise-like. Can one compute the spectrum ...
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1answer
26 views

how much time it takes for a flute to start making sound?

sound as i understand is created in a flute by ; the compressions imparted to the air inside the flute . the blowed air is also sometimes not allowed to enter the flute due to its regular contact with ...
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226 views

How does a flute produce its sound?

if an object for instance does not create successive compressions and rarefactions in air but only creates continuous compressions would we be able to hear these compressions as sound ? Yes , because ...
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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 ...