Questions tagged [acoustics]

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.

Filter by
Sorted by
Tagged with
-2
votes
0answers
25 views

Is it possible to hear sound if you are travelling at the speed of light? [closed]

If you are traveling at the speed of light, you are obviously faster than the speed of sound. Will the sound reach to us at speed of light as it does when at rest? If yes, what happens to radio waves? ...
-1
votes
1answer
22 views

What is the speed of Pushing/Pulling? [duplicate]

If there was a huge rod the length of a light-year in space and someone pulled one end of it, when would the other end move?
1
vote
0answers
17 views

How does tea kettle whistle?

Apparently no one fully understood the phenomenon until 2013 https://www.cam.ac.uk/research/news/how-the-kettle-got-its-whistle How I interpret what the article said was the steam goes through a ...
43
votes
4answers
5k views

Why does pitch increase when you blow harder into a whistle?

When you play recorder or whistle, the pitch depends on how hard you blow into the tube. E.g. when you blow a whistle, initially the pitch is slightly lower when there is less air flow. This seems ...
0
votes
1answer
14 views

Single-slit Fraunhofer diffraction within finite baffle/barrier

Many standard expositions of Fraunhofer diffraction from a single slit (such as here: https://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction) assume that the slit is situated in a baffle or ...
3
votes
1answer
57 views

Why would sound reverberate indefinitely in two spatial dimensions?

I came across this amazing fact that the sound propagation is distortionless only in odd dimensions, due to Huygens' principle (found in the abstract)[1]. Digging deeper, this webpage by Wolfgang ...
2
votes
2answers
97 views

Two Point Source Interference: Why No Interference Occurs When Source Separation is Shorter than Wavelength?

I don't quite understand why no interference would occur when the separation between the two sources is less than the wavelength of the wave. I can't find demonstrations about such special case on the ...
1
vote
0answers
27 views

Helmholtz resonance

I conducted my own Helmholtz resonance experiment with a glass voss bottle. The graph I obtained when plotting my experimental values of f against the reciprocal of square root V is plotted on the ...
1
vote
1answer
23 views

Average acoustics power of sound

We know that acoustics power of sound is equal to intensity of sound times area of the sphere centered with sound source, but my question is what is average acoustic power and if there is any ...
1
vote
1answer
43 views

Mach number at the throat of Convergence-Divergence nozzle

Why is it important to have a Mach number=1 at the throat of Convergence-Divergence nozzle? What if the Mach number at the throat is less than 1? Is a modification in the nozzle design required then?
1
vote
1answer
25 views

How does ultrasound imaging localize points in the $x$-$y$ plane?

Lots of sources describe how ultrasound imaging uses the time differences between wave emission and reception to calculate distances to points in the body. This makes sense for how localization works ...
1
vote
2answers
37 views

Acoustic/Sound waves in early universe

Friends, Sound waves, being mechanical in nature cannot travel in empty space. But I came across an article " Magnetic Fields in early Universe" by Dario Grasso and Hector R. Rubinstein in which it ...
2
votes
1answer
48 views

Why there's a displacement node at the closed end of an organ pipe?

Every textbook mentions that there's a displacement node at the closed end of an organ pipe. But the particles in air rapidly strike (or collide) with the closed end this can induce longitudinal ...
1
vote
2answers
23 views

Is there a subterranean SOFAR channel

After discovering the SOFAR channel in water at a depth which the speed of sound is at its minimum and acts as a waveguide, it was postulated that a similar channel existed in the atmosphere and ...
1
vote
1answer
35 views

Diagram for the standing wave in a singing wine glass

Can anyone help me find a proper illustration of a standing wave that comes as a result of the superposition of the travelling waves in a wine glass? I am looking for something like (from this video ...
25
votes
7answers
5k views

If sound passes through material, vibration is produced. So are electromagnetic waves produced too?

Sound means vibration of molecules and vibration produces electromagnetic waves. So, this means that sound produces electromagnetic waves directly. Is this possible?
0
votes
1answer
90 views

What is the property of sound that Allows it not to travel in vacuum?

What is the property of sound that makes it does not travel in a vacuum.
0
votes
2answers
53 views

Why do waves disappear after some time?

When a stone is thrown in water then transverse waves are formed. But they get slow and disappear after sometime. Why? Similarly it happens in longitudinal waves. When we speak, after sometime our ...
0
votes
0answers
28 views

Are impacts in outer space more powerful than on Earth? [duplicate]

Is an impact less destructive on Earth than on other planets with no atmosphere, given that the momenta, factors like the line of impact are identical in both cases? If yes, then is it because there ...
1
vote
1answer
39 views

Voice inside a room and outside [closed]

I think these are small questions which I would like to ask here as they are related with sound/acoustic. Hopefully I can get some helps as I am blind with physics. 1a. Say I try singing in my dorm ...
2
votes
2answers
74 views

At what speed does heat flow in materials?

When we heat one end of an iron rod on the stove, it takes a considerable time for the other end to be heated to the same temperature as the first end. On the other hand, as we know, the atomic ...
1
vote
2answers
33 views

Graph of periodic motion due to wave

Wave is a disturbance in a medium, due to this disturbance the particles in the medium oscillate. Due to this oscillation we say that the wave is sinusoidal because the motion of the particle is ...
4
votes
1answer
43 views

Normal modes of vibration of a plate vs a membrane

I have been studying Chladni patterns but recently I have stumbled on some conceptual questions that I seem to not have an answer. At first I thought that the theory would be the same of a vibrating ...
2
votes
1answer
51 views

What is the relation between the fundamental frequency and a harmonic?

I am currently busy with a physics report about determining the speed of sound in air. In order to do this, I was told to use a tube that can extend or shorten in order to find the different harmonics ...
1
vote
1answer
47 views

Is this true, the floor acts like one giant amplifier?

It sound like the tutorial is saying (a video link with a time stamp) soundproofing as i say it's all about density. it's also about transmission of sound through solid surfaces. so any two ...
1
vote
1answer
24 views

Is there some other measurement that describe the ability to absorb some spicified range of frequencies of sound?

There are a variety of materials could be used to absorb sound in order to soundproof. Absorption coefficient is used to describe the absorb sound ability of the material. Is the following guess ...
1
vote
2answers
42 views

How does this happen? downstairs neighbour constantly bangs in his kitchen while it sounds the noise comes from the ceiling?

I live in a build like the following image. I live in the floor pointed out by red arrow. One of my neighbors live in the floor pointed out by blue arrow, and he bangs in his kitchen all day long. ...
0
votes
0answers
30 views

Why adiabatic and reversible process is needed to write $\delta p = \frac{d p}{d\rho} \, \delta\rho$?

Consider a fluid in thermodynamic equilibrium, with pressure $p_0$ and energy density $\rho_0$. You then create a small local perturbation to produce a sound wave: \begin{align}\tag{1} \rho &= \...
1
vote
2answers
35 views

Why could resilient channel improve the sound insulation drywall?Are there some measurement?

This post says Resilient channel is a thin metal channel that is intelligently designed to substantially improve the sound insulation of drywall, sheetrock, plasterboard walls and ceilings. Why ...
0
votes
1answer
13 views

Motion of air particles across ultrasound waves

I wanted to know if air particles can cross through (transverse direction) an ultrasound wave or they will start to oscillate in the direction of wave propagation (longitudinal) when they get in ...
2
votes
2answers
35 views

Sound waves travel so fast. Hence how can they be considered a quasi static process?

Sound waves travel so fast. We apply the rules of adiabatic process (quasi static) to derive at the equation for speed of sound. My doubt is that how can sound be considered a quasi static process ...
2
votes
1answer
55 views

Why do my headphones hum under power lines?

Whilst walking under overhead power lines, I notice a bass buzz/ rumble in my Bose Bluetooth headphones, which seems to fluctuate in amplitude. I understand there is naturally a hum/ buzz around power ...
2
votes
1answer
38 views

Is this a complete list of phenomena that sound wave would encounter during travelling?

per wiki, Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of ...
0
votes
1answer
14 views

Absorption coefficients is composed 2 parts, is there any other quantity to measure only the transmitted part?

It seems that acoustic absorption is composed 2 parts: transformed into heat and transmitted through the absorping materials. In the context of soundproofing, in particular, acoustically isolated ...
10
votes
3answers
1k views

What happens when the amplitudes of interfering waves is different in the phenomenon of beats?

I had read that for the formation of beats, two waves must interfere such that they have similar frequencies but not identical, and their amplitudes should be identical. I don't understand why should ...
2
votes
2answers
35 views

Does an anechoic chamber take mainly effect on the sound from inside or outside the chamber?

per wiki, an acoustic anechoic chamber is a room designed to absorb as much sound as possible. The walls consist of a number of baffles with highly absorptive material arranged in such a way that ...
1
vote
1answer
14 views

What is the miminal volumn an acoustic anechoic chamber need to be? How to compute this quantity?

per wiki, an acoustic anechoic chamber is a room designed to absorb as much sound as possible. The walls consist of a number of baffles with highly absorptive material arranged in such a way that ...
-1
votes
1answer
34 views

There are 3 possibilities in total, namely, reflecting + transformed into heat + transmitted through the absorbing body, right?

per wiki, Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of ...
-1
votes
1answer
19 views

Does **object** refer to group of materials in a specified structure here?

per wiki, Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of ...
0
votes
1answer
25 views

Cound someone help to check if this paper is talking about sound absorption coefficient of the air?

I am trying to compute the distance I stand away from a sound source and still can detect the sound although I cannot hear clearly what the speaker is saying. Given the threshold of human hearing and ...
1
vote
2answers
43 views

Reflection of Sound Wave and Light (Electromagnetic) Waves from a Rigid Boundary

We know that when a light wave (Electromagnetic Waves) reflects from a rigid boundary, the reflected ray suffers a phase difference of "Pi" (180 degrees). But, in case of a sound wave, if it gets ...
0
votes
1answer
24 views

Could someone double check if my understanding about the area could one watt be spread over?

This tutorial illustrates how large of an area could one watt be spread over and still be intense enough for the human ear to hear it. It would be a trillion square meter. according to which, if ...
0
votes
0answers
14 views

Is there a list of sound absorption coefficients for common types of paper/cardboard?

I am looking for a list of Sound Absorption Coefficients for common types of paper/cardboard. I googled and got this list, which only has 2 items labeled "Paper Out". it does not seem to be ...
1
vote
0answers
25 views

Second sound in superfluids and solids

I am trying to get a handle on the phenomenon of second sound. It most famously occurs in superfluids at finite temperature. Here, according to Landau, superfluid phonons (which exist at zero ...
13
votes
1answer
1k views

Why are sound waves longitudinal even though they are mechanical energy?

Waves on a string, ripples on a pond are transverse waves generated by mechanical energy and in the simplest form oscillations. Sound also is a form of energy and basically oscillations. What makes ...
1
vote
1answer
21 views

What equipments/instruments do I need to determine the absorption coefficient of a cardboard box?

This post is not a duplicate of that post, which is discussing equations, while this post is discussing instruments, such as Decibel meter. I would like to build a bigger box with 26 smaller boxes, ...
2
votes
1answer
36 views

How to determine the Absorption coefficient of the material shown as follow? paper plus + air?

Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. wiki gives a table for ...
0
votes
0answers
59 views

Why don't cell phones pick up music in phone calls? [duplicate]

Why is it that a listener on a cell phone cannot hear music on the other end? For example, the source phone is located either in a car with music being played, or is at a concert. The listener hears ...
2
votes
1answer
100 views

Noise cancelling speakers to cancel sound in the room [duplicate]

A thought of mine from class, where not everyone is the "silent kid" type. The teacher would very often need to shout to keep the class barely quiet enough for the students who actually are paying ...
3
votes
3answers
34 views

Influence of ultrasound on air pressure levels

I am wondering if Ultrasonic waves can influence air pressure. Would there be change in air pressure in the order of Pascals where ultrasound waves pass?

1 2 3 4 5 39