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 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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268 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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457 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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834 views

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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243 views

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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1answer
474 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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260 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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695 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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Why, when one opens 1 car window, does that noise occur?

When you're driving and you open 1 car window, say the front one, there comes a horrible noise, but when you open another window just the slightest bit, this noise goes away (I'm sure most people know ...
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1answer
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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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2answers
254 views

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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701 views

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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651 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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281 views

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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2answers
211 views

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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1answer
316 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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208 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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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 ...
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Laws of aerodynamics after breaking the sound barrier

my knowledge of physics is not very extensive, so I hope my question isn't too stupid. I know that when (for instance) a plane breaks trough the sound barrier, the laws of the aerodynamics change. ...
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Is there an upper frequency limit to ultrasound?

Wikipedia has this diagram of the acoustic frequency spectrum: Is there an upper limit to the frequencies you can transmit through the air? Are they absorbed more and more at higher frequencies, ...
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Why does the sound pitch increase on every consecutive tick at the bottom of a filled cup of coffee?

Since I don't know the proper physical terms for this, I describe it in everyday English. The following has kept me wondering for quite some time and so far I haven't found a reasonable explanation. ...
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1answer
265 views

Why does music have a different tonality when heard from earphones a distance away?

Why when I have music on in earphones and I have them resting on a desk, the music sounds different, like in a different tonality/pitch to when I am actually using them?
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_Actually_ hearing the shape of a drum

The problem of hearing the shape of a drum is well known as a mathematical problem. But what about as a problem of (1) physics and (2) human perception? Suppose you have the kind of membrane used ...
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Difference in timbre between 'quiet' and 'far away'

I'd like to know what are the differences in timbre - or the acoustic properties of a sound - that allow us to differentiate between a sound which is quiet (but close-by) and one which is far away. ...
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How can people do music with Tesla coils?

I saw a lot of videos of Tesla coils doing music on YouTube. And I wonder how can they do that sort of things. How they can calculate what tone it is going to do? And what are the factors to ...
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Will timbre/quality be different if two different people play the same guitar? [closed]

Will timbre/quality be different if two different people play the same guitar? Assume that frequency/pitch and amplitude are same.
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1answer
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How does a speaker produce sound?

What I read is that a speaker produces sound by the movement of a coil attached to a cone which moves back and forth. So, If I try to move the coil by hand, would it produce sound? If not, why? or Why ...
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382 views

Does EM radiation (any, i.e. RF), or sound, radiate everywhere at once?

I am having trouble understanding electromagnetic radiation (or waves in general, be it EM or sound). If I have a 1 Watt speaker, is it infinitely divided and spread out so that everyone in every ...
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Riddle about speed

This stems from a riddle I read in a magazine perhaps 20 years ago so I apologise for the imprecise recollection. A dog that can run infinitely fast is placed on an infinitely large flat surface and ...
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Why can't echoes be heard inside a room?

If I go camping and shout anywhere, in the forest or on a cliff, I usually hear the echo of my voice. Why when I shout in my room I do not hear any echoes?
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How to distinguish female and male voices via Fourier analysis?

What makes one, without looking, be able to identify the gender of the talker as male or female? I mean if we Fourier analysed the voice of males and females, how the 2 spectrums are different which ...
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1answer
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Is it possible to break bulletproof glass with your voice?

In The Adventures of Tintin, an opera singer (the Milanese Nightingale) broke a bulletproof glass case using her voice. Is that scientifically possible? From the Wikipedia page, a typical bulletproof ...
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Why do bass tones travel through walls?

I was in the shower while my roommate was listening to music and got to thinking about the fact that I could only hear the bass and lower drums through the walls. Why is this? The two possibilities I ...
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1answer
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What theory is the person in this song talking about?

What he is talking about sounds interesting to me, and I would like to know more. But I need to know the name first. http://www.youtube.com/watch?v=Ogn5FrVGtAg&hd=1
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2answers
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Decibel level addition of multiple noise sources

If I have four computer fans of which each is said to run at 46 dB, and they run close to each other, how loud is the whole system? I somehow recall from my physics course that 10 decibel ...
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3answers
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How can a sine wave represent a longitudinal wave?

I envision a longitudinal wave as a series of vertical lines like that drawn on the board in an introductory physics class. This image contains no angles. Sound is a longitudinal wave. Some ...
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2answers
204 views

Drum head coupled with an RLC circuit

I'm thinking about the possibility of an electroacoustic drum that would be tuned with some kind of RLC circuit. The drum head would have an electromagnet attached to its center, which would be ...
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1answer
168 views

Is there a theortical limit to the amount of sound-energy air can contain?

is there a theoretical limit to the amount of sound energy air can contain? In case, there is a limit, what is that limit?
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The definition of “frequency” in different contexts

I have been doing some research on all kinds of sound-related topics lately and have been a bit confused by the different uses of the term "frequency". Of course, the most general meaning of frequency ...
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Why can I tell a flute from a trumpet?

The usual story I've heard describing the difference between a 440 Hz note played by a flute and a trumpet is that the overtones are different. That is, if you play a note at 440 Hz, there will also ...