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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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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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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Why does the sound pitch increase on every consecutive tick at the bottom of a filled cup of coffee?
Since I don't know the proper physical terms for this, I describe it in everyday English. The following has kept me wondering for quite some time and so far I haven't found a reasonable explanation.
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How can sound waves propagate through air?
We know that the sound waves propagate through air, and it can't travel through vacuum. so the thing that help it doing that is the air's molecules pressure. So my question how can that happens? I ...
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How can you focus sound?
I saw this TED talk and I am curious as to how the sound is focused on the general level. Can anyone explain this or does anyone have any good articles?
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Why does the note played by a flute not change in this case when the air column is interrupted?
I play the flute as a hobby, and I've noticed that when playing middle D or E flat, one can interrupt the air column by releasing a certain key (which is near the middle of the air column), and yet ...
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Hearing a sound backwards because of Doppler effect
Consider a supersonic plane (mach 2) aproaching a stationary sound source (e.g a fog horn on a boat).
If I understand it correctly, the passengers in the plane can hear the sound twice. First at a 3 ...
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Difference in timbre between 'quiet' and 'far away'
I'd like to know what are the differences in timbre - or the acoustic properties of a sound - that allow us to differentiate between a sound which is quiet (but close-by) and one which is far away.
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Why does water make a sound when it is disturbed?
When I disturb a body of water, what causes the familiar "water moving" sound?
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Is it possible to accelerate air to supersonic speeds? What would it look like?
The speed of sound is the rate that disturbances in air propagate through it.
Is it possible to have a wind that itself is moving at supersonic speeds relative to stationary winds around it?
Or ...
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How long do reflections take?
How long does it take for a photon to be reflected? Starting with the photon being absorbed by some atom to the point it's reemitted?
And what's the same point with pressure waves, like sound?
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Doppler effect “apparent frequency”
In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ...
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Superposition of electromagnetic waves
The superposition of two waves is given by
$$\sin(\omega_1 t)+\sin(\omega_2 t)=2\cos\left(\frac{\omega_1-\omega_2}{2}t\right)\sin\left(\frac{\omega_1+\omega_2}{2}t\right).$$
For sound waves, this ...
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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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When water is about to boil
Have ever noticed? When water is about to boil, no matters the kettle, there is some sound I have no idea where it comes from, sometimes long before it boils.
Is there any explanation for this ...
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The energy of an electromagnetic wave
The intensity of an electromagnetic wave is only related to its amplitude $E^2$ and not its frequency. A photon has the same wavelength as the wave that's carrying it, and its energy is $h f$.
So ...
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Doppler effect of sound waves
I am looking for interesting ways to introduce the Doppler effect to students. I want some situations in nature or every day life, where a student is possibly surprised and may ask "how could it be"?
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Design of a common table fan
A few questions about the design of a common table fan, such as below.
Does the round disc (silver in the image) in front of the blades serve any functional purpose?
Does the metal casing around the ...
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What is the relation of sound propagation to air pressure?
Hi there i am wondering, air is making sound propagate. So in vacuum there is no sound. but what is the relation of pressure to sound volume? is it linear?
if i have a source of sound and lets say i ...
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Modelling noise with distance
I was wondering about the relation between noise with distance, assuming a point source, using sound as the method for communication and air as the medium of communication. Obviously as the distance ...
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Potential functions
Can someone please explain what a potential is? Example. velocity potential in ideal flows, acoustic potential (gradient of which gives the particle velocity in a sound wave).
Whenever I see potential ...
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Frequency of the sound when blowing in a bottle
I'm sure you have tried sometime to make a sound by blowing in an empty bottle. Of course, the tone/frequency of the sound modifies if the bottle changes its shape, volume, etc.
I am interested in ...
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Why can't light pass through walls but sound can?
when i sit in a room....i can hear voices coming from the adjacent room but the light in adjacent room does not enter my room i.e. sound waves travels through the wall but light waves can't.why?
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Will timbre/quality be different if two different people play the same guitar? [closed]
Will timbre/quality be different if two different people play the same guitar? Assume that frequency/pitch and amplitude are same.
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Speed of sound in astrophysics
Why is the speed of sound given so much importance in Astrophysics? For example in gas outflow (and accretion) problems, we often calculate the sonic point (the point at which the outflow speed ...
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What determines the pitch of a resonant object
What determines what pitch an object such as a bell or tuning fork produces when struck? I have heard that the box in the "king's chamber" of the great pyramid at Giza is tuned to 438 Hz. I know that ...
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Resonance in a 1 ft granite box
I have a granite cube made using 6 slabs of granite 1 foot square and 1 inch thick. The top and bottom slabs have a 1 inch margin around the edge. The slabs are just set together, not notched or ...
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the sounds of an exploding star
We know that space cannot spread a sound wave as there is no "air" or a medium that would support the spread of a sound wave. However if we put ourselves in the vicinity of an exploding star, would it ...
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Remnant of a supernova
i explain better
A supernova remnant is the structure resulting from the explosion of a giant star . The supernova remnant is surrounded by an expanding shock wave that is formed from material ...
