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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possible causes of plastic cases cracking sounds [closed]
I have a very strange issue with many plastic cases in my room (tv, computer etc.) which very often make cracking sounds as if when cooling down after switching off - the problem is they crack all the ...
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7answers
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How can a black hole produce sound?
I was reading this article from NASA -- it's NASA -- and literally found myself perplexed. The article describes the discovery that black holes emit a "note" that has physical ramifications on the ...
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1answer
44 views
Is a sonic boom a one-time bang or a continuous noise?
Is a sonic boom a one-time bang, caused when an object initially goes supersonic, or is it a continuous noise emitted by the object as it's travelling?
To be more specific, will an aircraft which is ...
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1answer
34 views
Relationship between tones made by a piano
If a piano were to be tuned perfectly with the equal temperament system, what would be the relationship between standing waves from one note to the next? How would the frequency and wavelength of ...
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1answer
49 views
Energy in a wind instrument?
My physics teacher said that he saw a guy playing a very large wind instrument on TV, and the guy apparently calculated that the total energy present in the instrument when he was playing was almost ...
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1answer
26 views
Decibel equation, dyne or Watt
I know decibel is used as a ration between two same physical quantity on a logaritmic scale.
Is also used for calculate the intensity of a sound, but I found it reported in two different ways
db = 20 ...
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49 views
Ringing sound when you flip a coin?
When you flip a coin, you hear a ringing sound. I know that the source of the sound is the thumbnail hitting the coin, but it seems to be filtered by the spinning of the coin. Specifically, the faster ...
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24 views
Thermal Penetration Depth discrepancy
I've been working on a project that involves thermoacoustics, and one of the commonly-used values in this field is know as the thermal penetration depth. It is calculated as follows:
$$\delta_k = ...
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1answer
47 views
Why do higher pitches appear to be louder?
It may just be in a few cases, but in the case of a flute, a higher pitch appears to come with a perceived higher volume. Is this simply because you need to put more energy into the flute to get a ...
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1answer
552 views
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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1answer
39 views
High frequency sound transmission through plastic. I can't hear enough treble! [closed]
I have a large cylinder made of a rigid thick plastic with a speaker inside of it. I want to be able to hear high pitched / high frequency noise from the outside but I'm primarily hearing bass. The ...
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25 views
How to amplify a sound as much as possible acoustically? [closed]
It is possible to amplify a sound from a musical instrument by making sure that the vibrations that are created travel through a so-called 'sound box'; The body of a guitar is a sound box that ...
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1answer
245 views
Why is light produced when an underwater bubble is collapsed with a sound wave?
Why is light produced when an underwater bubble is collapsed with a sound wave?
I have come across this fact on a page (similar to this) but can't understand "Why". I'm just curious about this ...
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2answers
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How to compute the speed of sound in relativistic hydrodynamic?
In Weinberg: Gravitation and Cosmology chapter 2.10 (Relativistic Hydrodynamics) the speed of sound is derived as
$v_s^2 = \left(\frac{\partial p}{\partial \rho}\right)$
and the equation of state ...
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Echo of a sound whose source is moving away from the wall [closed]
A girl walks. She is $50m$ in front of the wall and she begins to sing. Find when she will hear the sound echo if she recedes from the wall at $2m/s$. The temperature is $12^0 C$.
I don't know where ...
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Bass and Treble-Car Steroes
In a car which phenomenon, diffraction or the resonant frequency of the car, lends itself more to the ability of bass to go farther?
Related Answer: Why do bass tones travel through walls?
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1answer
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Varying the amplitude of a driven wave
I' d like to know whether varying the amplitude of a system at resonance is possible or not and if it is, how? I've calculated the resonance frequency of a material and I'd like to know the ...
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7answers
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A Musical Pathway
Using a small number of sound emitters, could you create a room where certain nodes emitted particular tones, but no meaningful sound was heard anywhere else.
So, for example, by walking down a ...
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1answer
45 views
A Doppler Effect problem with a moving medium
I tried solving the following question and started having multiple doubts:
Two cars A and B are moving towards each other with some speed $25$ m/s. Wind is blowing with speed $5$ m/s in the ...
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1answer
46 views
Hearing sound around corners
I've been taught that diffraction is the reason why we can hear around corners, since the wavelength of sound is approximately 10 cm (smaller than a door or a window).
I wonder how can this be ...
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2answers
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Increase sound intensity in a wall [closed]
Why it seems that a sound transmitted in a wall is more intense (amplified)?
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1answer
53 views
Can random constructive interference with sound waves cause damage?
Any two sound waves have a random chance to constructively interfere with each other at a given spot and this will cause an increase or decrease in pressure. So is it possible that a large number of ...
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1answer
379 views
Ultrasonic wave through air
I am not a physicist but I am extremely interested in this area.
The simple version of my question is:
"What is the maximum range of an ultrasonic wave traveling through air?"
Now, I know it depends ...
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Why does sound move faster in solids?
I know that the molecules are closer together in solids, and I know thicker springs also respond carry waves faster than thinner springs, but for some reasons I can't understand why.
The molecules ...
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1answer
163 views
Acoustic Metamaterials: Negative Bulk Modulus?
In acoustic metamaterials we have simultaneously negative bulk modulus, $\beta$, and effective mass density, $\rho$.
I understand how one can obtain a -ve $\rho$ by constructing a solid-solid system ...
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2answers
152 views
Does altitude affect sound pitch?
Due to differences in air pressure, temperature, and other factors, the speed of sound varies with altitude on Earth. Does this affect the pitch of the sound in any meaningful way?
For example, if I ...
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1answer
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Can we apply de Broglie's relations to sound waves?
Can we apply the de Broglie relations to a sound waves ?
Is it possible?
if yes how do you do that?
what would be the mass(m) in the equation?
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1answer
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Manufacturing Fresnel Lenses with Sound
I understand fresnel lenses are manufactured using CNC machines. I was wondering, if it would be possible to use sound to vibrate liquid silicon and then fast cool it into the standard form of a ...
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Fourier transformation in nature/natural physics?
I just came from a class on Fourier Transformations as applied to signal processing and sound. It all seems pretty abstract to me, so I was wondering if there were any physical systems that would ...
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2answers
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What are the limitations of performing music in space?
Canadian astronaut Chris Hadfield's song Space Oddity is making news around the world today. It makes me wonder: What are the limitations of performing music in space? Clearly, there is no point to ...
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1answer
52 views
Crackling of Speakers-Audio
Why do speakers make crackling noises when the pitches get too high for them? And why is it that lower end speakers tend to crackle more? If you try to feed in too high of a frequency, I would imagine ...
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1answer
114 views
Why do sound waves travel at the same speed moleculewise? (Same medium)
I don't understand what happens in reality (outside of wave theories). If I clap my hands I invest energy in the nearby air molecules, which move and transfer their energy to nearby molecules which ...
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72 views
Slinky reverb: the origin of the iconic Star Wars blaster sound
This is a fun problem that I came across recently, which I'm posting here for your delectation. We all love a good slinky: they can be used for all sorts of fun demos in physics. One example is the ...
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2answers
653 views
How can a Human voice or animal voice have unique frequency
Well this is pretty noobish question and I am not sure how to ask.
When We talk we don't talk in an uniform frequency. Then how can one measure frequency of ones sound/voice ?
I am asking this cause ...
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3answers
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Lethality of sounds and extreme “loudness”
In theory, could pure sound be lethal? How loud would it have to be? Also, which events are the loudest in the universe, and how loud are they? I'm confining attention to events which occur regularly, ...
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1answer
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Is there a naturally occuring sound pressure level reference?
There are lots of devices that purport to measure the absolute value of sound pressure levels. Here is an example, here's another, there's also this iPhone App. Putting such devices side-by-side in ...
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1answer
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Rolling sound of thunder
When sound of thunder travels to the listener from its location,different parts of the same wave have to travel through air of different moisture levels,densities and molar masses.
This is what I ...
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3answers
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Polarization of sound
The sound can't be polarized beacuse the vibration of such type can't be polarized beacuse the vibration of such type can't be limited or controlled by any barriers and so polarization is not possible ...
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Why does the fundamental mode of a recorder disappear when you blow harder?
I have a simple recorder, like this:
When I cover all the holes and blow gently, it blows at about 550 Hz, but when I blow more forcefully, it jumps an octave and blows 1100 Hz.
What's the ...
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How much information about the scale of a waterfall can be obtained from its sound?
Is it possible to constrain the height, volume flow, or distance of a waterfall from the quantitative analysis of a high-quality recording of its sound?
As an aside, the simulated sounds of fluid ...
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4answers
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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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3answers
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Waveguides (in the ocean?)
The speed of sound in the ocean is given by
$$c_s(\theta,z) = 1450 + 4.6\theta - 0.055\theta^2 + 0.016z$$
$\theta$ is the temperature in degrees celcius, and $z$ is the depth. In a simplified model, ...
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1answer
59 views
Why do cold metal plate make less noise?
I have a metal gate in my home so I have noticed that when it is a hot day and if I hit it it makes a lot of noise but when there is a rainy day and the weather and the gate re cold and if I hit the ...
5
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2answers
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In terms of the Doppler effect, what happens when the source is moving faster than the wave?
I'm just trying to understand this problem from a qualitative perspective. The Doppler effect is commonly explained in terms of how a siren sounds higher in pitch as it is approaching a particular ...
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1answer
53 views
How to determine frequency components present in distorted signal, with the set of possible components already known?
I am trying to choose the best approach to digitally analyse a signal, which is a mix of an unknown number (but less than 16) fundamental signals at specific frequencies (e.g., sines).
The goal is ...
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4answers
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Would a phone move upon vibration in a completely uniform situation?
I was sitting down yesterday and saw my phone vibrate on a side, and it moved about a centimetre per vibration.
I wondered why it moves, and thought perhaps that the side it was on had a slight ...
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2answers
235 views
Maximum delay for effective active noise cancelling?
Active noise cancelling reduces unwanted sound by sending the inverted phase of the original phase:
(Source: Wikipedia)
Theoretically, this seems logical to me. However, in real life, the ...
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1answer
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How does one find the wave velocity and the phase speed?
While I was studying beats, I tried to find a displacement function of any particle in the most generalized form. I ended up with $$y=2A\sin(\pi(t-x/v)(f_1+f_2))\cos(\pi(t-x/v)(f_1-f_2)).$$
Now, ...
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3answers
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Accelerating faster per second than the speed of sound?
What would happen if you were to accelerate one end of a material, say a steel rod for instance, at faster per second than the speed of sound in that material?
For example, if the speed of sound in ...
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1answer
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Whistling on bottle tops
It is well known that if you blow horizontally on a bottle top it creates a sound. Pouring water to the bottle changes the pitch.
I have been doing experiments on the relation between the sound's ...
