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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What is the name for the whistling “musical” sounds that change stepwise in pitch when a hollow tube is spun like a lasso?

You have likely heard those sounds, science museums sometimes sell Flexible plastic tubes you can whirl like a lasso. The air rushing by the end of the tube causes these sounds, which are admitted in ...
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Why does the balloon pop?

When we pierce a balloon with a sharp needle, it pops and produce a great sound. But, It doesn't pop when we open the mouth of the balloon (through which we have blown air)... So, Why doesn't the gas ...
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Did Felix Baumgartner produce a sonic boom during his jump?

I really got to thinking about this. The speed of sound is measured at 761.2 MPH at sea level. But how does this number change as air density decreases? The lack of air density is what allowed his ...
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How is sound produced at the atomic level?

How is sound produced looking from the atomic level? My thought process goes like this: Atoms are not perfect circles/solid spheres which we use to describe many macroscopic/classical phenomena.They ...
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Science behind the singing wine glass

A wine glass filled with water (approximately half or a quarter), when you use a wet finger and rub the top of the wine glass, the wine glass will produce a sound. I heard that it is because of the ...
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Doppler effect “apparent frequency”

In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ...
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153 views

Microphones, Loudspeaker and their analogies to spring mass system

I have just started studying Microphones and Loudspeakers. I need a good text to refer which can explain their mechanical analogies with simplicity and basics too.
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Can we compute the magnitude of the stress caused by sound waves on a wall?

As a follow up to this question, Could we really compute the magnitude of the stress caused by sound waves on a wall? If so, How do we do that?
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Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
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Fundamental frequency , wavelength and the length?

What is the concept behind when it is said that for the first fundamental f=c/λ , λ should be equal to 2L . I have read the page http://en.wikipedia.org/wiki/Fundamental_frequency but I am still ...
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Eigen modes in a room

In a rectangular room 10*8*5 how can the eigen modes belonging to octave and third octave bands centered at 50Hz be found ? I have the formula to calculate the number of modes but don't have the idea ...
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Is it possible to hear the past?

From this Stack Exchange Physics Post, I am certain that it is possible to view the past. But then this interesting question came to me. Is it possible to hear the past? Ok, you might say, "Well, ...
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Why can't light pass through walls but sound can?

When I sit in a room I can hear voices coming from the adjacent room but the light in adjacent room does not enter my room i.e. sound waves travels through the wall but light waves can't. Why?
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Does the human body have a resonant frequency? If so, how strong is it?

Inspired by this question on Music beta SE, I'm wondering if the human body has a strong resonant frequency. I guess the fact that it's largely a bag of jelly would add a lot of damping to the system, ...
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speed of sound and the potential energy of an ideal gas; Goldstein derivation

I am looking the derivation of the speed of sound in Goldstein's Classical Mechanics (sec. 11-3, pp. 356-358, 1st ed). In order to write down the Lagrangian, he needs the kinetic and potential ...
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Why does inverting a song have no influence?

I inverted the waveform of a given song and was wondering what will happen. The result is that it sounds the exact same way as before. I used Audacity and doublechecked if the wave-form really is ...
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496 views

the sounds of an exploding star

We know that space cannot spread a sound wave as there is no "air" or a medium that would support the spread of a sound wave. However if we put ourselves in the vicinity of an exploding star, would it ...
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Visualise the sound intensity

I'm studying Biophysics and my current subject is sound. One of the properties of sound is intensity. From my notes I can see the following definition: Intensity Formula is: $(I = w*m^{-2})$ or $(I = ...
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What does it mean to increase volume by X decibels?

I am trying to decipher what decibels are: http://en.wikipedia.org/wiki/Decibel It seems to be a log ratio of audio amplitude multiplied by a constant. I am confused by what this means though. If ...
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Why does a wobbly metal sheet make the sound of thunder?

In other words, what is the similarity between a lightning bolt and a wobbling sheet that make them sound alike? It seems to me that the two systems have a much different way of moving the air, and ...
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can sound travel is space?

Everybody knows that sound cant travel through space, but is really valid? Here is my scenerio: Given the size of a football field's length cubed, there are two objects at two opposing sides. the ...
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743 views

Why doesn't sound travel through walls?

If sound travels better through denser material, why does the sound travel better without a dense wall?
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Why does thermal resistance go down as temperature goes up?

Here is the thermal resistance data for three speaker coils disengaged from the speaker cone. Any ideas? I would think it would be a horizontal line. http://en.wikipedia.org/wiki/Thermal_resistance ...
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Why and how is sound produced when two objects hit each other?

When two objects collide and undergo a partially inelastic collision (so every one we experience in every-day life), they rebound to a certain degree, but kinetic energy is not conserved. Thus, the ...
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Why does the note played by a flute not change in this case when the air column is interrupted?

I play the flute as a hobby, and I've noticed that when playing middle D or E flat, one can interrupt the air column by releasing a certain key (which is near the middle of the air column), and yet ...
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Sound frequency of dropping bomb

Everyone has seen cartoons of bombs being dropped, accompanied by a whistling sound as they drop. This sound gets lower in frequency as the bomb nears the ground. I've been lucky enough to not be ...
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How can sound waves propagate through air?

We know that the sound waves propagate through air, and it can't travel through vacuum. so the thing that help it doing that is the air's molecules pressure. So my question how can that happens? I ...
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Speaker cabinet to improve sound of mobile phone loudspeaker (music) [closed]

I want to experiment with an enclosure for my phone so the frequency response has a little more punch at the bottom end. I understand that something can't be created from nothing, but enclosures work ...
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265 views

Sound “exploding” in car's window at certain speed [duplicate]

Possible Duplicate: Why, when one opens 1 car window, does that noise occur? My knowledge in this area is really out-of-dated and stopped somewhere like ten years ago. So I would like to ...
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452 views

Physics of a guitar

I understand that when you pluck a guitar string, then a bunch of harmonic frequencies are produced rather than just the frequency of the desired note. If this is true, why does C2 sound so different ...
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Frequency Specific Sound Reduction And dB Levels?

I started with a DIY construction project pertaining to sound-proofing; but now I'm feeling overwhelmed by a lack of knowledge on the physics of sound. I've learned that sound reduction techniques ...
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Sound Produced due to motion of air inside a tube

I'm trying to understand the sound produced by Air motion inside the respiratory system. If you have a long tube with a suction apparatus at one end , You turn on the apparatus and the air is sucked ...
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The sound of coffee [duplicate]

Possible Duplicate: Why does the sound pitch increase on every consecutive tick at the bottom of a filled cup of coffee? A colleague suggested this experiment this morning : Get a cup of ...
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470 views

Open Ended/ Close Ended instruments?

Close ended instruments have twice the wavelength, because the wave must travel twice the distance to repeat itself. Why must a wave reach a lower density medium (air in this case) to repeat? When ...
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257 views

Loudspeaker frequency response dip

I'm trying to determine the reason for a dip in the frequency response curve of my loudspeaker. I have a loudspeaker mounted on the inside of an enclosure, and a 100mm ID tube mounted in-front of the ...
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668 views

Resonance and Natural Vibrations in Vacuum

In my Physics textbook, it says that if two pendulums of the same natural frequency are placed next to each other and if one is set into vibration, the other starts resonating and when the first one ...
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What is the roaring in a roaring fire?

I was just starting a barbecue fire by blowing on the smouldering coals when I realised I had no idea what the sound was actually caused by. I can make the sound by blowing at almost any flame I can ...
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Can sound be separated from air?

I would like to open up a window in my house, let the air in, but keep the sound out. Could a device be designed to put up on the window, like a screen, and accomplish this?
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Sound waves through a glass filled with liquid

I was pondering about the following 'experiment', and was curious about the formulae behind it. Imagine having a glass filled with a liquid. On one side there is a sensitive receiver that records ...
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650 views

speed of sound relative to density of medium through which sound travels

I know that sound travels faster in water compared to air and say faster in steel than in what're so What would the density have to be to cause sound to approach the speed of light
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Will a black hole increase the speed of sound above the speed of light in this medium

For the sake of this question we are inside the EH and a sound wave enters from our perspective as the sound moves closer to us at the EH would it speed up. Specifically how would the extreme ...
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The energy of an electromagnetic wave

The intensity of an electromagnetic wave is only related to its amplitude $E^2$ and not its frequency. A photon has the same wavelength as the wave that's carrying it, and its energy is $h f$. So ...
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How can I use sound/resonance to clean sewers?

This probably doesn't fit into the realm of regular questions ; it is more of an applied rather than theory/math question ... Anyway, I'm curious whether a metre diameter speaker fitted over a ...
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301 views

noise level (units confusion)

i had a question in one of my classes regarding SNR in underwater acoustic channels. There are a couple of terms with the unit dB re uPa. I know it stands for dB ...
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206 views

What is the cause of noise generation at my bike helmet

I am looking for anexplanation of this phenomenon: I was riding my bike, (not driving it, was sitting on the back seat) with the helmet on. While the glass of the helmet was intact, I could hear ...
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Superposition of electromagnetic waves

The superposition of two waves is given by $$\sin(\omega_1 t)+\sin(\omega_2 t)=2\cos\left(\frac{\omega_1-\omega_2}{2}t\right)\sin\left(\frac{\omega_1+\omega_2}{2}t\right).$$ For sound waves, this ...
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3answers
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Why is there a 90˚ phase angle between particle velocity and sound pressure in spherical waves?

My text says that in a plane sound wave (or in the far field), particle velocity and pressure is in phase. As we move closer to the sound source (to near field and more spherical waves), the phase ...
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How does the energy of a sound wave decrease with the distance

More precisely, how small is the potency a listener hears, compared to the potency of the emitter. I'd like to present a simple and yet reasonable approximation, to a high school audience (I am a ...
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How does one derive the equation for the speed of sound?

In my acoustics books I see $$c^2 = \frac{\mathrm{d}P}{\mathrm{d}\rho}$$ where $c$ is the speed of sound, $P$ is the pressure and $\rho$ is the density. Where does this equation come from? In my ...