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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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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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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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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82 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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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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74 views
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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32 views
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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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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41 views
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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31 views
Increase sound intensity in a wall
Why it seems that a sound transmitted in a wall is more intense (amplified)?
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Questions about noise impact on living organisms [closed]
What do we use to measure objective volume and subjective volume?
How is the intensity of the sound depends of the distance of the source to the detector?
How does the intensity of the sound change ...
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1answer
56 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 ...
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83 views
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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40 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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108 views
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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4answers
79 views
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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69 views
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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101 views
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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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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91 views
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 ...
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3answers
137 views
Frequency of a Tuning Fork
Question: Which of the following affect the frequency of a tuning fork?
Tine stiffness
Tine length
The force with which it's struck
Density of the surrounding air
Temperature of the surrounding air
...
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2answers
74 views
Independence of frequency in sound waves?
Why does the frequency of sound wave depend only on the source? Why is the frequency and not any other "quality" independent of everything but the source?
And that said, why is velocity and ...
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35 views
Focused 200 K sound [closed]
How can a 200K sounds wave be focused? I am trying to make an acoustical spotlight. The 200K sound wave will be amplitude modulated. Any help that you can provide will be greatly appreciated. ...
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Water excitation with sine waves
I saw that video when they connected a water hose to a speaker emitting 24 hz sine wave, and its illusion on the shape of the follow going out of the hose (because the video capture rate is fixed at ...
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87 views
Why do we hear a higher pitched sound out of water when we hit two stones against each other in the water?
The observer is outside the water; the stones are underwater (say, 1 m below surface, if that matters). This produces a higher pitched sound for the observer than when both the observer and the stones ...
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147 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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Sound as a conserved quantity
From the first man to the present day men, all of them have made some sound. Sound is an energy, it can neither be created nor can it be destroyed. Therefore, every word spoken by each human that came ...
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Calculating the mass equivalency of a song?
I've recently become fascinated with the idea of sound energy having a theoretical equivalent mass. I've read over this thread:
Do light and sound waves have mass
I understand this part: ...
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Can light waves cause beats?
My question is pretty brief. When two sound waves of nearly same frequencies interfere, we get beats.
But, I have not observed something like that happening in the case of light. In fact, most of the ...
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52 views
Why it happen's when I rub my finger's?
I have a pc with a metallic body on my CPU case. Yesterday suddenly the earthing wire of my CPU broke down and I was able to feel a little bit current on touching it's metallic body. But what I found ...
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54 views
Sound of packing tape dispensation?
I am sitting in a cigar lounge, and under the jazz music playing I can hear this strange, rising and falling tone, that sounds similar to one of those weird tubes you can find at a fun fair. You tilt ...
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75 views
Acoustic wave equation for a closed sphere
I am looking to model the nodal surfaces in a resonating closed sphere. The sound source is external. What sort of wave equation will reveal the spherical harmonics depending on the frequency, speed ...
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audio signal arithmetic
BACKGROUND:
I have been messing around with audio signals in Audacity and realized that by inverting a signal and adding it to the same signal I get no signal. Thus (S + invS) is really (S-S). (S+S) = ...
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Whistle Physics
I'm looking for a simple explanation of how a whistle operates. I know that forcing air over a sharp lip can set up a wave in a resonating cavity, but how? "Most whistles operate due to a feedback ...
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Sound Wave Propagation: Why HF are more specular while LF are more omni
The propagation of high frequencies sound waves is more directional (specular), and they don't diffract as much as low frequencies. Low-frequencies diffract and thus propagate in a more omni-spherical ...
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2013 Russian meteor event, Sonic Boom or Explosion Boom?
In the lastest meteor event in Russia there was a big BOOM heard long after the meteor had passed. In this youtube video we can see at 4:30 the Meteor passing.. then hearing the BOOM at 7:00 , 150 ...
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269 views
Calculating displacement amplitude of ultrasonic power transducer
I am not a physicist, but my current project drives me to some physics-related computations, hence seeking help.
I have some ultrasonic transducers, 5938D-25LBPZT, for which very limited information ...
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Sum and Difference Frequencies - Amplitude Modulation
I understand that while transmitting an envelope through a carrier wave to the receiver, an upper sideband and a lower sideband form adjacent to the carrier wave. The sidebands are apparently an ...
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Can a sound mathematical formula become a science theory?
Can a sound mathematical formula become a science theory if it is constructed using a pattern creation process from sense-data, applied to observations by an inductive mapping, in contrast to ...
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Active speakers picking up cellular tower waves?
Since a week or so a constant high pitch sound (~4khz) emanates from my active monitor speakers. After eliminating any ground or power source issues I noticed, that the sound rises in volume whenever ...
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Does sound propagate further in freezing weather?
A few days ago I went for a walk in the evening. We're having winter with a little snow and freezing temperatures. We're in a quiet, shallow valley with a train station about 1km from us. I heard a ...
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296 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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1answer
192 views
Reflection of sound waves
I was doing a physics experiment, and i encountered a question which i couldnt answer. The experiment was about using a radar technique to measure the speed of sound. The apparatus was a plastic tube ...
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15 views
Blocking mass Or Inter layer in terms of noise transmission
I am studying the application of a Blocking mass and Interlayer when placed between to semi-infinite beams or plates,having bending wave propagation,in terms of noise transmission.My question is based ...
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2answers
116 views
Orthogonality of modes
I want to know what it exactly means when it is said the modes of vibration are Orthogonal.I understand what it means mathematically but what is its physical interpretation?
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How does sound travel in space?
In relation to this question:
How can a black hole produce sound?
Which notes that the hole "produces" sound. The top answer states that:
What you think of as the hard vacuum of outer space ...
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What information is stored on gramaphones/tape recorders/CDs/DVDs
I'm a Software Developer by profession and my physics knowledge is limited what I had learned at high school level. Please excuse me if the question is trivial.
Question:
From what I know, a sound ...
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How come vibrations?
We all know that sound sensation is produced only when sound waves reach upto us. We all know that sound waves are disturbances propagating in air, Vibration is necessary for the generation of sound, ...
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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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Speed of sound in air
Quick question. I thought that the speed of sound in air was constant, say in the right conditions of pressure and temperature, and humidity... 300 m/s. Now, if I have a sound source that moves ...
