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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Two superimposed sounds traveling through low- and high-density matter: is separation possible?

Two superimposed sounds (at source: $s(t) = s_1(t) + s_2(t)$; the two sound components overlap completely in time, partially in spectra) travel through low- and high-density matter and are recorded ...
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70 views

Frequency of Sound Waves

Is the frequency of the echo (resulted from the reflected sound wave) equal to the frequency of the original sound wave?
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46 views

The amplitude of oscillations in sound waves

How can the amplitude of molecules displacement be measured in a sound wave? How can the amplitude of the pressure fluctuation be measured in a sound wave? What are the difference between these two ...
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192 views

Is the change in cochlear potentials dependent on perilymph velocity? [closed]

context: This question may appear to be off topic because it is about the biological particulars of the human ear. Physics can solve abstract models inspired by living organisms, but it is biology ...
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111 views

How does a sonic black hole (or dumb hole) work?

I came across this term and I heard they used sonic black holes to detect something analogous to hawking radiation, but I have failed to find sources which explain how exactly they work and how they ...
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112 views

How would a sound mirror work?

Context: We all know that by galvanizing a plate with a silver coating, this plate will have a very high reflection coefficient and act as a mirror for EM radiation (not for all $\lambda$ ranges of ...
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51 views

Is the speed of sound related to the speed of impact?

What will be the end result of the following experiment: I take two "identical" buckets of water and a hammer. I strike the surface of the first bucket with a low speed and measure the speed of the ...
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52 views

Rayleigh criterion for sound and parabolic microphone

Currently I am developing a parabolic microphone for a study project. I've heard and read that the maximum wavelength of sound that the given diameter microphone can focus is determined based on the ...
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12 views

Reason for audio speaker diaphragm shape [duplicate]

Why are the diaphragms on audio speakers usually a cone with a dome in the centre? I don't know much about acoustics but my guesses would be: it just empirically sounds better, the design was found ...
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Why is it so easy to create audible sound?

Context Why is it so easy to create audible sounds in life with basically anything? Putting your cup of coffee on a table comes with a sound Turning a page of your book comes with a sound Even ...
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106 views

Interference of sound: how to calculate the sound intensity at each point?

I need help with the following question: Two speakers are sending out sound in phase with the frequency 2,13 kHz. The sound from the speakers is registered in three points A, B and C. See figure. ...
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73 views

How does resonance store vibrational energy?

In the wiki article, it is written that in resonance, maximum amplitude is possible as vibrational energy is stored. What does that statement mean? How is energy stored so that max. amplitude ...
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19 views

Loud, low-frequency “booming” sound in car [duplicate]

I drive a Scion XD, and I've noticed that whenever I drive at about 40mi/hr or so with just the back windows rolled down, I get a loud "booming" effect at roughly 10Hz. What causes this? I assume it ...
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72 views

Why does the bass range of phase mismatched speakers show more interference than the treble range?

If stereo speakers are connected to the amplifier "out of phase," one speaker is moving outwards when the other is moving inwards.This results in a weakness in bass notes, which can be corrected by ...
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109 views

For creating beats how small the difference should be between the two frequencies

It is said that to create beats we need two "slightly" different frequencies, and subtract it. 1- My question is why do we need slightly different frequencies? Why not large difference? 2- Also ...
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31 views

Good references for mathematics of sound attenuation? [closed]

I am looking for recommendations for good references for mathematical modeling of sound attenuation.
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0answers
47 views

Can we hear on Mercury, since the atmosphere is so thin? [duplicate]

Since the atmosphere of Mercury is very thin, and only contains negligible amount of Oxygen, Hydrogen, and Helium, can we hear the sound over there? can the sound be transmitted by some mean?
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186 views

Why can a person in a noisy room not hear someone outside the room, yet the the outsider can hear the person in the room?

If I'm in a noisy room (radio on, babies splashing in bath, etc.) I struggle to hear someone shouting to me from outside the room. Yet to them, my voice comes through quite clearly. What causes this ...
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393 views

How does an acoustic guitar amplify its sound?

An essential part of a guitar is its hollow body. Without it, the strings wouldn't be very loud; as far as I know, the purpose of the body is to set up some sort of resonance and make the sound ...
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790 views

Why is a whistle sound emitted when air is pushed through a tight space?

Seems like a simple enough question: Why is a whistle sound emitted when air is pushed through a tight space?
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102 views

Is there a relation between music chords and visible light palette [closed]

Ok I have no idea if this is the right stackexchange so if you know who would know please tell me :) In music there are groups of notes that, when played togheter, are basis to harmony. Since both ...
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1answer
46 views

Air Presure and Air Velocity from speaker

How do I determine/calculate the air pressure emitted from a speaker ? And how to determine the velocity of air from the sound air pressure ?
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29 views

Ray tracing a three-way intersection

I've been studying ray tracing in media with linear velocity-depth functions. One of the key concepts I've come across is the ray parameter, and in particular the idea that the ray parameter is ...
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2answers
102 views

Why need for 96kHz, 192kHz audio? [closed]

Human can hear 20-20,000 Hz waves, so by Nyquist theorem it's sufficient to sample audio with 40 kHz. Indeed, 44.1 kHz widely used. But what do we need higher sample rates for? 96 kHz, 192 kHz are ...
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Bell vs. diaphragm of stethoscope for low frequency sounds

Why is the bell of the stethoscope used to hear lower frequencies if it has a smaller diameter than the diaphragm? I would have thought that a bigger diameter diaphragm could pick up lower frequency ...
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1answer
106 views

Why do empty vessels make more sound?

Why do we hear a roaring or humming sound when an empty bottle is held close to our ear ? When I hold a flask close to my ears, I hear like a sound which coming from its interior.
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170 views

Why Light isn't like an Acoustic wave?

I just wanted to know why light isn't an Acoustic wave.Is it because light wave doesn't obey acoustic properties?
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How much air needs to be displaced to generate an audible sound?

I'm reading a book where in one scene a wizard/alchemist teleports a scroll after reading. He folded the parchment carefully and muttered a single cantrip. The note vanished with a small plop of ...
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161 views

If a tree falls in the forest [closed]

The question of whether or not a tree that falls in the forest makes a sound - if there is nothing or no one around to hear it - comes up frequently at my house. So, my question is: is there any way ...
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107 views

Sound power radiation of two monopole sources

For a fixed given electrical power to two monopole sources, producing the same frequency. Which mode, either in-phase or out of phase, will radiate the most sound power into the far-field?
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387 views

how does air pressure affect the speed of sound

How does air pressure affect the speed of sound in relation to its kinetic theory etc? I have tried searching this but i have not found a suitable answer as other websites simply related to air ...
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114 views

How to create a barrier for sound waves?

Is there a way to create a barrier so that sound waves cannot pass through? Does laser light have this ability to act as a barrier or bounce sound waves back? This came to my mind when I was ...
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20 views

What's responsible for dull or sharp sounds in a struck sintered rods?

I've sintered a number of rods from powdered oxide materials, and some of them ring clearly after being struck (not as clear as, say, a metal tube, but clear enough to hear a definite pitch), while ...
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16 views

Will a sodium bell ring clearly after being submerged in liquid nitrogen?

Lead is fairly soft at room temperature but rings clearly when cooled to liquid nitrogen temperatures. Sodium is even softer. If cooled to liquid nitrogen temperature, could it also ring?
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256 views

Is it theoretically possible to have a universe where sound travels faster than light $c$? [closed]

We all "know" nothing can travel faster than light. However, if we're allowed to tweak the fundamental constants of nature, is it theoretically possible that such an universe might exist? Update: I ...
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173 views

Why does the pitch of a container being filled with water increase? [duplicate]

I wonder about this. If you pour water in a closed tank, it makes a noise. I have noticed that as the container becomes more and more full, the pitch of this noise also increases. Why is that? I do ...
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90 views

How much of the chemical energy in a burning log is released as sound?

Firewood has energy content of about 15 MJ/kg for hardwoods. You throw one of these hardwood logs onto a fire hot enough that it burns with, say, 50% efficiency. How much of that energy will be ...
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20 views

The supersonic bandwagon

I happen to stumble upon this intriguing animation of a Tachyon, and immediately started to think about the same phenomenon, but with sound waves. I imagined a bandwagon ...
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63 views

Rubbing finger, where's the frequency come from?

When I rub my finger against a piece of rubber, and it makes a tone of 2 kHz, what is vibrating at 2,000 times per second in order to produce that tone? The rubber doesn't feel flexible enough to ...
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92 views

Source of low frequency oscillation heard in ambulance siren

I have noticed that when I am standing on the street as an ambulance passes that so long as it is sufficiently close by (within 10-15 feet, so the siren is VERY loud for this to happen), I hear a ...
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6answers
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The sound of rotating helicopter blades

Why do helicopter blades make this pulsing, oscilating, slapping(?) sound? Since their movement is smooth, shouldn't the sound be a similar, constant shush, perhaps increasing or decreasing in ...
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1answer
104 views

Is a sonic boom loudest when source is at exactly Mach 1?

Please imagine this cartoonish thing: a flying loudspeaker, playing a continuous sound, with zero air resistance (i.e its moving through the air doesn't generate any whooshing sounds) is coming ...
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477 views

Is it possible to use “negative sound waves” to “cancel out” a sound to create silence?

I saw youtube videos that claimed to do this, although I'm quite certain the videos just excluded sound and lied. However, I am wondering if the physics of this is actually possible - to create a ...
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163 views

Help me understand resonance

I don't fully understand how resonant chambers work. My confusion stems from the fact that the chambers are passive elements or filters, yet somehow are able to amplify the sound. Questions: How ...
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4answers
179 views

Sound diffraction through a single slit

When sound waves diffract through a single slit, do they produce an interference pattern which is mathematically identical to that of light waves in the corresponding experiment?
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26 views

Can anyone provide a good exposition on acoustic impedance?

Can anyone provide a good exposition on acoustic impedance? Does anyone know of a good paper or textbook that does so? It seems like most sources kind of just start using it without deriving any ...
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2answers
102 views

Surface acoustic wave

Why does a surface acoustic wave (SAW) propagate only in the surface leyer of the solid, let's assume a semiconductor? One can create such a SAW through an interdigital transducer (IDT) as I read, ...
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1answer
140 views

Speed of sound and Break the sound barrier

What happens when plane exceeds the speed of sound? and What is the interpretation of the conical shape that appears behind the plane?
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209 views

Sound Wave interference Experiment

I was wondering, can we use two sound sources so as to create a destructive interference at the position of a recorder at home? If possible, what is the easiest way?
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65 views

Frequency dependance of sound wave reflection

Why are high frequencies reflected more than low frequencies off an 'acoustically hard' surface such as concrete? I basically understand that the amount of reflection is determined by the impedance ...