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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Apparent frequency and wavelength in the Doppler effect

For a transverse wave(or for pressure waves required to produce longitudinal waves), the motion perpendicular to the direction of propagation of the wave is governed by an equation like $y = ...
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Is it possible to realize either the bucket is full or not from sound?

If a bucket is hold under a tap and the tap is open to full the bucket with water, is it possible to understand from the sound of falling water either the bucket is full or not? Are you able to give ...
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39 views

What are the differences between beat and interference?

For two waves, if it can be seen that after an interval of time no sound is heard, which option is liable for this incident? One option is interference of sound, and another is beat. I know that beat ...
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63 views

Does sound have a “louder” direction?

I have a question about the propagation of sound waves. We have two TV's in our house that are almost right on top of each other. One is located on the first floor and the other one is located on ...
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1answer
54 views

Can I create a device which will create silence? [duplicate]

Sound waves in opposite phases will cancel each other out. Is it theoretically possible to create a device which will record the sound and output sound in opposite phase which will result in ...
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218 views

How can I hear if something is behind or in front of me?

I wonder how I can hear what direction a sound is coming from. I believe that the brain calculates relative to the volume from each ear, meaning I'm unable to know what direction a sound is coming ...
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51 views

Which modes are excited when a drum is struck?

I've been searching quite extensively for an answer to this question but I cannot find anything definitive. The most I can see is that "one or several" modes become excited, but this is never ...
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50 views

How can I make the nastiest fingernails-on-blackboard type sound? [closed]

We all know how nasty the fingernails-on-a-blackboard sound is. What can I do to make a sound of this kind which is as loud and nasty as possible? This doesn't have to involve any particular ...
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23 views

Calculating the frequency produced by a rectangular piece of metal

I have a rectangular prism made of steel. Its dimensions are 0.1 cm x 0.2 cm x 12 cm. If I screw one end to a stable object and vibrate the other end. How would I calculate the frequency produced by ...
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20 views

Recording microwave oven from the inside [closed]

I was wondering if's possible to record the sound from a microwave over from the inside. Not only with a regular mic but also with a 'telephone pickup coil'. How can I do this without damaging the ...
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19 views

How to derive the Sperically symmetric Wave Equation (in spherical coordinates) using first principles? [closed]

I want to use first principles (of mass and momentum conservation) on a spherical shell and derive the wave equation given below, where $p'$ is the pressure perturbation : $\frac{\partial^2 ...
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11 views

What bang / boom sounds do not invoke supersonic propagation?

Explosions, supersonic booms, whiplash sounds are usually supersonic phenomenona. What sort-of common bang / boom sounds are there that do not involve supersonic propagation ? Or is this a "wrong" ...
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26 views

Pressure wave in a cup of tea casued by a bubble burst

Assume there is a cup of tea with bubbles formed on its surface by the inner wall of the cup. If one of the bubbles bursts, it causes a wavefront travelling on the surface of the tea. Is this wave ...
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41 views

Relationship Between Acoustics and Gravity?

I have studied some physics in college, but not enough to know the answer. My motivation: sound (or acoustics in general) does not exist in a vacuum, which means that acoustic waves are only present ...
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1answer
19 views

What does a goniometer (sound) show?

In looking into 2D representations of audio, I came across a tool called a goniometer. I'm aware that a goniometer refers also to a device for measuring angles, but in this context it refers to one ...
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31 views

Transmission of Sound Waves [duplicate]

If a tree falls in a forest and no one is around does it still make a sound ? I know the answer is supposed to be no, because the sound is created when it enters someone's ear. What if I left a tape ...
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97 views

Why do I hear a deep rumble when I cover my ears?

Probably a trivial thing but a simple google search didn't show anything relevant about it. If I cover both of my ears with my hands, I hear a very deep rumble. If I slowly move my hands away the ...
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67 views

Why can we produce a sound by blowing across a blade of grass, a paper strip or similar

I just don't know how is the sound produced? Does it come from the vibration of the blade of grass or the air in the up and down?
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60 views

Resultant frequency if 3 harmonic notes (a chord) is played

If I know the frequency of individual notes being played (let's assume D, F# and A), how do I determine the final frequency if they are played (nearly) simultaneously as a chord. To put the problem ...
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49 views

Why does sound become louder and increase frequency if I give it a narrow path?

If I put my hand over the speaker of my phone like in the picture, I can clearly hear my music amplified, why does this happen? The only cause I can think about is the fact that all the intensity ...
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799 views

How quickly is motion transferred in a solid object?

Just for example: assume an iron bar one foot in length. If you push on one end, the entire bar will move. This seems instantaneous. but actually, from my understanding, the atoms all push against ...
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3answers
81 views

Is it theoretically possible to project sound in a line, like flashlights?

I was wondering if there is a way to project sound waves on a particular point, like a laser? So that you can you can privately send a voice message to a specific person in crowd. The very first idea ...
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50 views

Voices of Animals And Humans

What are the differences between voices of animals and humans? (Not by ear but by a program or similar...frequency, other things) Does each animal in each species have a unique voice? Is there a ...
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1answer
94 views

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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49 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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34 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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127 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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38 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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67 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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1answer
31 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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23 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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11 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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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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33 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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18 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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58 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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3answers
75 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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25 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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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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26 views

How do sound wave interact with a bubble?

When a sound wave propagates in a medium consist of liquid with a bubble, what cause oscillation of the bubble? Negative pressure of sound cause drop of pressure in both liquid and bubble ...
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102 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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76 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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736 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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66 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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28 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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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
68 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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55 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.