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 does the sound of a tuning fork change as we walk away?

This is a question I got for my class. We have the following situation. We take two tuning forks, we hit them, then we take one of the tuning forks and walk away with it. The sound changes as we walk ...
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2answers
66 views

what could generate a high-pitched whine in electronics where the frequency depends on the current?

So I was operating a Laue machine recently which generates x-rays and fires them at a sample, and I noticed that there was a high-pitched whine coming from the instrument (nothing abnormal, just ...
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96 views

Does sound cancel itself out?

If there are two 10 x 2 x 1 foot rectangles in space and they are lined up so if they hit each other there will be no spots that are not hit in the front of the rectangle. Then they are pushed forward ...
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43 views

Sound localization using cross-correlation

I am using cross correlation for sound localization. I have a four microphone array (arranged linearly). My problem is, sometimes the time diff found by cross correlation between a given pair of mics ...
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72 views

Why are waves, the means, of information transfer over long distances, excluding difusion or contact of info stored in matter

Practical long distance communication, which does not rely on the movement of encoded configurations of matter, from source to destination(odor,books,DNA,floppy disk), always involves waves (EM, ...
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78 views

Why does this cowbell appear to vibrate at the wrong frequencies?

The cowbell in question: http://www.youtube.com/watch?v=OuU0BzXm-qk In most cowbells, the larger the metal dome, the lower the frequency produced. What would cause a phenomenon where the opposite is ...
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78 views

At what frequency would a quartz crystal shatter?

Would it be possible to emit a sound at such a frequency that a quartz crystal inside of a watch would shatter? (Rendering the watch useless)
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1answer
126 views

The Mysterious Reverb in a Jar of Hair Gel

I have a small jar filled with hair styling gel (or, as it calls itself: Ultra Gel-Wax). The jar is cylindrical(with the height being less than the width), has an unscreweable lid and is made of ...
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1answer
58 views

Algorithm to simulate impulse response of a solid?

There are well-documented methods of calculating the impulse response of a room (ex. image method, ray-tracing method); however, I have not been able to find anything similar for the impulse response ...
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1answer
155 views

Speed of sound in non-newtonian fluids

Recently I saw some videos of non-newtonian (shear-thickening) fluids like corn starch mixed with water(sometimes known as oobleck), where the fluid is placed on top of a speaker cone and starts to ...
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1answer
282 views

How to Calculate temperature, given speed of sound and relative humidity?

I know the solution in reverse direction, but I find it very complex to go the other way around and calculate the temperature when given the speed of sound and relative humidity, any ideas?
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37 views

Sound Intensity Measurements convert to Sound Power

If you need to have Sound Power results and the location that the microphone needs to be to make the measurement(per the standard) is not accessible. There is a machine part in between the ...
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1answer
172 views

How does concave bowl amplifies the sound?

I recently came across an article / answer in Quora see here that mentioned that if we place the iPhone in a bowl and play music, the volume is amplified. What is the physics principle behind this?
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196 views

Relationship between Stoke's law of sound attenuation and the inverse square law

In attempting to find a reference for explaining sound propagation, I came across this article in Wikipedia: Stokes law(sound attenuation) What I learnt in high school is that sound is propagated by ...
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1answer
127 views

If the source of sound is vibration, why can't we “hear” a object whose molecules are vibrating?

According to our physics textbook, the source of sound is vibration. According to our chemistry textbook, substances in solid state have molecules vibrating in a fixed position. So why can't I hear my ...
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0answers
48 views

Why does the echo of the last chord appear to rise in pitch

I - and others - observe that when a musical performance ends, the echo of the last chord appears to rise in pitch by up to a quarter tone while the echo decays. This effect appears to be independent ...
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1answer
162 views

How to determine the positions of two points in a radial line by an intensity level dB?

The following is the question from my school. A source emits sound uniformly in all directions. A radial line is drawn from this source. On this line, determine the positions of two points, 1.00m ...
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1answer
91 views

Why the sound won't still forever?

Let say we have a microphone and a speaker. The microphone will receive the surrounding sound, and the speaker will make it loud to play. Assume, we have unlimited power for microphone and speaker, ...
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1answer
324 views

Simple explanation of relation between speed of sound and r.m.s. speed?

In an ideal gas, the speed of sound $v_s$ is related to the r.m.s. molecular speed $v_m$ by $$\frac{v_s}{v_m}=\sqrt{\frac{\gamma}{3}} \qquad ,$$ where $\gamma=C_p/C_v=7/5$ for a diatomic gas. I ...
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1answer
97 views

The Doppler effect in a medium like air (sound) versus the electromagnetic Doppler effect

When you have a listener and a source, and when one of the two move relative to the other, the frequency perceived by the listener will be different. Example: If the listener travels toward the ...
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4answers
94 views

What are those characteristics by which every sound can be identified uniquely?

I have very basic question regarding sound I tried to search it over google but couldn’t find the right answer, my question: ...
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32 views

Is it possible to estimate the number of people in a room from a limited number of simultaneously recorded audio samples?

Note: I struggled to decide the appropriate site for this question, between http://physics.stackexchange.com/, http://avp.stackexchange.com/, http://math.stackexchange.com/, and even ...
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39 views

Nonlinear waves and shock formation

In the cases of nonlinear acoustics, why is shock formation unlikely when the dispersion is strong when compared to the nonlinearity of the wave?
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What is the meaning of “frequency of a human voice”?

The term frequency for a periodic wave can be defined as the number of times a repeating pattern occurs in a given time period (eg: no. of crest and trough cycles per second for EM wave). But what ...
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1answer
390 views

Resonance Experiment

Today in high school physics class, we performed an experiment on the resonance of sound, with a set up like this... To put it simply, the sound waves are supposed to rebound with the surface of ...
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2answers
131 views

Can a sound like a sonic boom change a object like a wall? And how the light on the walls will be changed after a sound like this? [closed]

Can a sound like a sonic boom change a object like a wall? And how the light on the walls will be changed after a sound like this?
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38 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
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1answer
38 views

How could you minimize sonic boom at the ground level?

I've heard that one of the reasons that we don't have commercial supersonic flight is because of the sonic boom produced. Is this really a deal-breaker and if not, how do you get around/minimize the ...
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1answer
267 views

Open pipe resonance

I read somewhere, a closed pipe has resonance with a sound of wave length 4 times the length of pipe (from open end to closed end), when putting a source above the open end (since it reinforces the ...
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1answer
114 views

'Push' in a rigid rod travel at speed of sound or speed of light [duplicate]

Two person, $A$ and $B$, each holding one end of a long solid rod. Now person $A$ pushes the rod on one end. Question: Is it correct that the information that the rod has been pushed will travel ...
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1answer
326 views

Why do you only hear high frequencies when a microphone is near its speaker?

The phenomenon I'm talking about is positive feedback, as known from control engineering: when the microphone is too close to its speaker, it can "hear itself", so the signal will be infinitely ...
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2answers
419 views

Why does a glass breaks when subject to very sharp sound like in opera?

I have seen in Ripleys believe it or not that an opera singer generates a very high frequency of sound and breaks a glass window.How do they do it?
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1answer
119 views

Why is there a sharp cracking sound when we break a plastic ruler?

Why is there a sharp cracking sound when we break a plastic ruler? The question appears to be simple and common but I need a apropriate answer.
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290 views

Heating coffee by yelling?

Is it a myth that yelling to a coffee mug will heat it? I have been hearing my friend saying that screaming will heat coffee or water.
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146 views

Relative velocity of sound

Relative velocity of sound. As I know that speed of sound in medium is property of medium. And independent of source motion but depend on motion of audience or observer and motion of medium. But it ...
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1answer
112 views

Do asteroids create sonic boom while entering the atmosphere?

Because of the lack of any materials to propagate sound, it can't spread in space. There's the air in the atmosphere, but its volume mass increases constantly (either linear or exponential, I don't ...
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3answers
256 views

Measuring speed of a vehicle

I'm very primitive with my thought. So please help if you can in layman terms with an answer to this question. Here we go- by using a street power pole as the source responder, is it possible to read ...
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2answers
359 views

How small can you be and still hear?

According to my understanding, at the smallest level sound is just a collection of particles colliding on a wave. So, assuming we can arbitrarily reduce the size of any human being, how small can we ...
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1answer
176 views

Steel rod to Mars vs the speed of sound, how is supersonic travel possible?

I remember reading this passage in the "Feynman Lectures", where Dr. Feynman describes an experiment in which a theoretical metal rod of length equal to the distance between Mars and Earth is arranged ...
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2answers
316 views

FFT distortion, harmonics (singing wine glass)

I'm doing a school assignment on Singing Wine glasses (you rub the rim of the wine glass with a wet finger and it produces a pure tone). I have recorded $30\,\text{ms}$ of the "singing" at a sampling ...
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3answers
373 views

How do human ears distinguish the frequencies in sound?

If they do a Fourier transform, how can they know the formula to find coefficients?
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1answer
88 views

Impact Force versus Non-impact force why are they so different?

A mass that has velocity and a force f1, can create a sound and even break a wall upon impact. However if the same force f1 is applied to the wall without any motion (velocity) then the wall will not ...
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1answer
175 views

Is sound relative?

Is sound relative? For example, if I and my friend are having a ride at 1000 mph and I shout towards him (speed of sound 700 mph). What would happen? Will the speed of the sound relative to the ...
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0answers
48 views

Harmonics of an infinite cylinder

If a hypothetical cylinder was infinitely long, could it vibrate at any frequency, since any frequency would be a harmonic of it? And (less hypothetically) if a cylinder was only really long, would it ...
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1answer
614 views

What part of the fan blade actually does the noise generation?

I'm trying to identify the sources of noise in spinning fan blades and what causes them. Is the noise only generated by the lead edge of the blade 'cutting through' air? and different parts of it ...
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1answer
117 views

How can I validate a numerical model using an analytical solution of the same scenario?

In the course of my research project I have been tasked with validating an acoustic model, however I am having trouble conceptualising what I am supposed to do. I have found an analytical solution for ...
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1answer
111 views

physical difference between A and B

We all know that when we say A it sounds different than when we say B. I was wondering what exactly can be the difference between saying A and B in terms of physics. I first thought that it may due ...
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0answers
39 views

is it possible to load a transversal wave with a longitudinal wave

like in communication engineering for sending information what we do, we take a high frequency carrier and modulate it with the message signal so can we do the same thing like take a high ...
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1answer
94 views

Sound Propagation using Finite-Difference Time-Domain (FDTD) considering wind effects

I am trying to plot the propagation of sound from a fixed source in a 2D environment using Finite-Difference Time-Domain (FDTD) Method taking into account the effects of the wind velocity. I came ...
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503 views

Is a sonic boom a one-time bang or a continuous noise?

Is a sonic boom a one-time bang, caused when an object initially goes supersonic, or is it a continuous noise emitted by the object as it's travelling? To be more specific, will an aircraft which is ...