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 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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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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160 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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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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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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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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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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42 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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56 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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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 ...
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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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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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41 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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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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50 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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28 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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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 ...
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How can pressure and velocity fluctuations in acoustic plane waves be in phase and still hold to the B.C. that velocity must be zero at a solid wall?

In linear plane-wave acoustics (no mean flow, small perturbations, etc.), it is often derived that the phase of a traveling pressure fluctuation wave and a fluctuation velocity wave are the same. For ...
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Audio attenuation over distance

In a completely open space, we position one speaker. The speaker emits a sound at X dB. How can I calculate the sound's volume at a specific distance? Also, how can I calculate the attenuation of a ...
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66 views

How can a harmonica make some different sounds?

My first post: I have found an interesting harmonica here. So, I tried to know more about harmonica. And, I have read this article , in which the author doesn't mention the physical calculation, ...
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675 views

Why does sound not travel between media?

So imagine you're at the beach; you go into the water and the moment you enter the water you stop hearing anything from the outside world. The same happens vice-versa: your friend shouts at you from ...
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78 views

Do electromagnetic waves produce sound?

Preamble: At 5 AM in the morning, if I sit quietly and listen attentively, I can hear many different noises, on a very high frequency. If I try to isolate the ones that are less noisy, I can clearly ...
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83 views

Is it possible to create an optical medium where sound can travel faster than light?

The speed of light decreases with increase in the density of the optical medium whereas the speed of sound increases with increase in the density of the medium. So is there any possibility to ...
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Amplitude of a sound wave [closed]

What is the largest displacement of an air molecule for a sound wave of 261.6 Hz with intensity 1 $\frac{W}{m^2}$? I am not sure how to find the energy of a sound wave.
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Diplacusis - possible to tell which ear is normal?

Diplacusis is a hearing disorder in which the two ears hear the same sound as different pitches. Suppose we know that someone with diplacusis has one normal ear and one ear that is slightly off. Using ...
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What will limit the speed at which one can play the piano?

I thought about this as a fun question. Suppose we provide a piano player that is limited only by the typical relativistic rules (i.e., hands and fingers cannot move faster the speed of light), so ...
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assumptions about sound waves

When deriving the sound wave equation: $${1 \over c^2} {\partial^2 p' \over \partial t^2 }= \Delta^2 p' $$ by linearizing the Euler equation: $$\rho {d v \over dt }= - \nabla p $$ and the continuity ...
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Crest in Light Doppler Effect

The way it is explained in wiki Doppler effect in sound happens because waves of particles with biggest density called crest hits our eardrums more often if object is moving towards us (increased ...
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How does superfluid helium interact with ultrasound?

Containing liquid helium in it's superfluid state is of course known to be problematic. Escape by crawling up container walls to 'leak' through solid containers and similar difficulties being a ...
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98 views

Can acoustic waves travel through human body?

If I stand inside a perfect anechoic chamber in front of a unidirectional acoustic waves emitter, I would hear the tone played either using my ears or using a microphone for ultrasonic waves. But what ...
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58 views

What causes loud sound when popping a baloon/bubble?

As I chew my gum, I wonder: when I blow and pop bubbles, what creates the snapping sound? Or similarly, what causes the loud POP when one pops a balloon? Is it the rush of air from inside the pocket ...
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Optimizing the second, third,… eigenvalues - applications

I'm working on some topics related to spectral optimization as a function of the domain. For example it is known for almost a century (lord Rayleigh and Faber, Krahn) that the shape which minimizes ...
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64 views

Magnitude of tension in a bent string

I understand tension in a straight string as a reaction force to a weight, which acts along the string, ultimately resulting from the attractive forces between the constituent particles of the string. ...
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Why does hot water and cold water makes different sounds while filling a bucket from a tap

When I fill hot water in a bucket while bathing, there is a difference in the noise it makes compared to cold water. Is there any Relation between temperature of water and sound it makes during ...
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What experimental evidence shows that sound velocity is the same for all wavelengths?

I'm studying sound waves with Halliday's book, and after reading the whole chapter, one of the questions suggested was: What is the experimental evidence that allows the assumption that the sound ...
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92 views

Physical intuition on vortex sound generation

Whenever a fluid has a nonzero vorticity, it looses some of its energy in a form of sound wave. Formally is this mechanism described by Lighthill's equation or some related model (like e.g. Curle's ...
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what is the relationship between the diameter and frequency of a driver?

What is the relationship between the diameter of a speaker/woofer, and the frequency it is capable of reproducing?
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What does a blackbody sound like?

Update: According to this wikipedia article, blackbody radiation is just thermal noise (Johnson–Nyquist noise); if that's what I'm looking for, what does it sound like? If a blackbody has a ...
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60 views

How can one change the virtual position of a sound source with a fixed array of speakers?

I have a question about signal processing: How to make a person, sitting between array of two loudspeakers (one from the left and one from his right), hear the sound that came from both loudspeakers, ...
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146 views

How loud would a sound have to be to be heard around the world?

I'm reading the book Cosmos by Carl Sagan, and in it he states: Striking the Earth's atmosphere, a modest cometary fragment would produce a great radiant fireball and a mighty blast wave, which ...
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Acoustical wave equation from Hamilton's principle

It is common to show the features and power of the Hamilton's principle by deriving the equation of vibrating string, membrane etc. using this principle. But I have never seen that used for deriving ...
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Waves and osciilation [closed]

When intensity of sound increases increases to 10 times level of sound increases by 10 decibel why and how the sound intensity is related to sound level
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What it sounds like when I'm travelling at the speed of sound

totally hypothetical here: lets say a man is playing a song on a guitar and I begin travelling quickly away from the guitar, if I were to reach the speed of sound, what will I hear? (my assumption ...
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Do sound waves travel before Big Bang?

So I was reading a Scientific American article about how the universe is spreading apart and how it is getting faster. But in the article there was something that baffled be and it was this "Sound ...
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Why don't choir voices destructively interfere so that we can't hear them?

Sound is propagated by waves. Waves can interfere. Suppose there are two tenors standing next to each other and each singing a continuous middle-C. Will it be the case that some people in the ...
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Sound wave in a Vacuum

If a Tuning fork was Struck in a Vacuum what happens to the resonant frequency of the fork and the potential sound wave. Does the wave leave the fork?
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60 views

How to detect “noisiness” of sound wave?

Some phonemes like "ssss" are basically white noise. How would you determine which parts of a wave are white noise? From frequency analysis the white noise will have no tones so just using this would ...
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46 views

How to derive end-correction value relationship for open-ended air columns?

According to Young and Freedman's Physics textbook, in open-ended air columns like some woodwind instruments, the position of the displacement antinode extends a tiny amount beyond the end of the ...
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The Speed of Sound [duplicate]

Just a question about Physics I'm doing at school. If the speed of sound is inversely proportional to the density of a material, why does sound travel faster in solids (it is the most dense). I have ...
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does the Fresnel approximation apply in the far field?

Most sources I've looked at treat far field diffraction and near field diffraction as separate cases, with the former using the Fraunhofer approximation and the latter the Fresnel approximation. In ...