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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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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102 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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140 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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117 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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13 views

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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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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150 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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38 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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50 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
56 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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42 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
74 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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117 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
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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4answers
460 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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2answers
34 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?
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25 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
58 views

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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1answer
28 views

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
33 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
548 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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4k views

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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3answers
126 views

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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24 views

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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276 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
40 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
65 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
84 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
23 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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37 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
36 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
110 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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32 views

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 ...
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1answer
183 views

Sound waves creating bubbles in water

Sorry for the title, couldn't find a better one. A few years ago I read on a scientific magazine about a discovery, but I can't remember the name nor find anymore information on it. Basically they ...
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36 views

Why does audio wave look like a wave? How to prove

I have googled for answer but, did not get any satisfactory result. I want to know that, why does audio wave or in general sense radio waves look like a wave. I mean basically how to prove that when ...
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1answer
84 views

Intensity of a standing sound wave at displacement nodes?

We know $$P = F\cdot v$$ where $v$ is the velocity vector. Since at the "displacement nodes" in a standing sound wave the velocity of the particles is always 0, the Power must be 0 and hence the ...
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30 views

How does mic combined with loudspeaker work? [closed]

There is variety of loudspeakers on the market that have built-in microphone so that they can produce sound and perceive it at the same time (and do it surprisingly well). How they managed to ...
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1answer
64 views

Literature on scientific achievements in physiological acoustics after Helmholtz [closed]

I'm greatly interested in theoretical/mathematical/physiological aspects of music and the corresponding acoustics. As everyone knows, the Greek already discovered that consonant sounds seem to ...
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2answers
44 views

How exactly can a speaker produce the huge number of frequencies in musi at he same time? [closed]

I know the basics of how a speaker works, but when I think about the fact that just one sound from an instrument has many frequencies happening at once and there are other sounds such as the guitar ...
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2answers
72 views

Could a single impulse be classified as a sound wave?

If not, how many counts(cycles) of impulses are needed before we can call it as sound(without 20-20000Hz limit)?
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17 views

Diagonal patterns in a Chladni plate experiment [duplicate]

I am an undergraduate student that's taking physics classes and have been assigned a seminar concerning Chladni figures. I understand the theory behind it, the standing waves in 1D and 2D, Bessel ...
3
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0answers
45 views

Proof that fixed points of a null field are zero

Suppose we have a scalar field $V$ (which can be acoustic pressure, or a scalar electric potential) that is a solution of the wave equation $$\Box V(x,y,z,t) = 0$$ I am wondering if a fixed ...
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57 views

sound propagation at low pressure

I am curious about the properties of sound at low atmospheric pressure. Not the speed of sound, I want to know how lower pressure will affect the distance sound will carry and the frequency range. For ...
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1answer
53 views

How is sound affected when reflected off a vibrating membrane?

When sound produced at a frequency, say 200Hz is reflected off a vibrating membrane, vibrating at another frequency, say 10Hz, what are the properties of the reflected wave in terms of frequency and ...
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1answer
78 views

What is the mechanism that moves an air molecule backwards in a sound wave?

I am attempting to understand the mechanics of a longitudinal sound wave. I understand that as a material vibrates, it pushes air molecules forward as it moves towards the direction of the wave. For ...
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2answers
54 views

What are the limitations of recording very faint sounds?

Is it possible to record very faint sounds like, say, the bending of a strand of hair? Part of the problem, I imagine, would be the need to find a way to isolate the target sound from other sounds. ...
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2answers
80 views

Getting the length of an open tube with only a frequency and temperature given? [closed]

I've got a rather strange question here. I need to find the length of an open tube (silver flute), but I have only been given the frequency of the note that it is playing and the outside temperate (as ...
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1answer
53 views

For an object in circular motion, does speed affect the amplitude of sound it creates? [closed]

First of all, I'm sorry if this is a stupid question and I've missed something obvious. I used to have an instrument that was a small drum tied to a piece of wood. When you hold the wood and swing the ...