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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What properties define a good resonator?

In my question "Resonance in a 1 ft granite box", someone answered that my granite box (a one foot cube) would make a very poor resonator, which makes me ask what characteristics make a good ...
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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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859 views

What's the difference between photoelastic constant, photoelastic coefficient and the acousto-optic coefficient

I'm reading a few papers about how the optical properties of materials change when a under stress or a force acts upon them. I seem to be encountering the following three terms: Photoelastic ...
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Does clipping to $m$ guarantee a maximum peak-to-peak amplitude $m$?

There is a technique called clipping in sound synthesis. It is explained on Wikipedia . I make music and like this technique: You make an extreme "fat" noise, maybe with a lot of resonance, but then ...
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569 views

Why does a smaller acoustic impedance mismatch produce lower transmission?

I'm attempting to solve a relatively trivial problem, but cannot seem to convince myself the answer I'm getting is true. I have two scenarios. Scenario 1. An acoustic wave propagates from Medium W ...
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Why does the monitor make a cracking noise?

After switching off the monitor, there's a single crack after a while. I wonder where exactly it comes from. I know that this is normal and not an indicator of being defect. This sound is also not ...
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74 views

Sound intensity and space/things in the way

Suppose you have two stationary people, A and B, who are equally effective in terms of hearing ability, and A emits a sound that is heard by B at a certain intensity. If they remain stationary, and B ...
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How would natural (resonant) frequencies affect amplitudes?

I read $y=A\sin(2\pi ft)$, where $A$=Amplitude, $f$=Frequency, $t$=Time and $y$=$Y$ position of the wave. Since natural frequencies only take the most effect when they are close to the frequency. How ...
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Is it possible to reduce the sound, when two metal objects collide (perhaps with some coating) without reducing the rigidity of the surface?

I have a system, where there are ball bearings on the pistons that clamp the metal plate with special dents for ball bearings. The system should be precise, because it is used for microscopy. It also ...
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52 views

Non reflecting boundaries in waveguides

Can someone please explain the Sommerfeld radiation condition and what is the alternative non-reflecting boundary conditions for waveguides of general geometries?
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Design and use of the RLC model for signal processing systems and spatial acoustics

Given a frequency response for a signal processing device, set of devices, or physical space it is possible to construct an equivalent (identical frequency response) series RLC circuit. 1) Does this ...
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How to relate speed of sound with relative humidity?

I am exploring the idea of measuring the humidity of a space using sound waves, however I am having trouble finding a mathematical relationship between the speed of sound and the humidity level. ...
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Does light have timbre?

Timbre is a property associated with the shape of a sound wave, that is, the coefficients of the discrete Fourier transform of the corresponding signal. This is why a violin and a piano can each play ...
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Why does the echo for soundwaves hitting a vacuum come back out of phase? [duplicate]

Possible Duplicate: Phase shift of 180 degrees on reflection from optically denser medium I've read in a physics book for musicians that, when a soundwave hits a near-solid object, it ...
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Meaning of negative frequency of sound wave

Suppose that Alice and Bob are both holding speakers emitting sound at a frequency $f$. Alice is stationary while Bob is moving towards Alice at twice the speed of sound. In the case of Alice, if I ...
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486 views

How to find the distance of the source of sound in this problem? [closed]

On a cloudy day, the sound of thunder was heard 4.5 s after the flash of light was seen. How far was the cloud? Given that speed of sound = 340 m/s This is what I've tried: speed of light(c) = 10^6 ...
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490 views

How do you find the speed of sound in the problem? [closed]

A stone is dropped into a 40m deep well. The sound of the splash is heard 2.95 seconds after the stone is dropped. Find the speed of sound.
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Why does my natural whistle have a maximum volume

When I whistle, I find that I can vary the volume by pushing more or less air through my mouth at once. However, when I increase volume past a point, I start to hear a blend of rushing air and a ...
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105 views

The Effects of Moving Matter Across Light-Year distances

If I were to stand at one end of a light-year long metal pole, and another person were to stand one light-year away at the other end, and then I were to push on my end of the pole. How long would it ...
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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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Energy distribution between long- and shearwaves after refraction of sound

From this explanation, I learn that sound is refracted according to Snell's Law upon passing a border between materials of different sound speed. I also learn that upon passing the border, a mode ...
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Octave equivalence: biological or more?

I'm a graduate student in mathematics doing a bit of research in signal processing and Fourier analysis and I've come across a question that could probably be better answered by a physicist: Is the ...
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589 views

Is a soundproofed wall really only as strong as its weakest area?

I've seen a few questions about sound waves and sound travel here on Physics SE, so I'm hoping this question is a good fit for this site. During my internet research on soundproofing, I've come ...
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Physical difference between two different attenuation coefficient functions

The attenuation of a wave through a medium can be modeled by the Beer-Lambert Law using an attenuation coefficient. If $I$ is the intensity, and $I_r$ is a reference intensity, then what is the ...
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What arrangement of sound waves would be needed to heat air in a typical sized room?

From what I understand, sound is simply the jostling of the molecules that make up the air in a specific pattern, widely known as waves. I also know that these are longitudinal waves. If we were to ...
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Is it possible to travel at precisely the speed of sound?

I've been talking to a friend, and he said that it's impossible to travel at exactly the same speed as the speed of sound is. He argued that it's only possible to break through the sound barrier using ...
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What characterizes a metallic sound, and why do metals have a metallic sound?

We know that when we strike a metal, it usually has a characteristic "sharp" sound, unlike when we strike wood, say. What characterizes this "metallic sound"? Does it have a well-defined power ...
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What is the name for the whistling “musical” sounds that change stepwise in pitch when a hollow tube is spun like a lasso?

You have likely heard those sounds, science museums sometimes sell Flexible plastic tubes you can whirl like a lasso. The air rushing by the end of the tube causes these sounds, which are admitted in ...
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Why does the balloon pop?

When we pierce a balloon with a sharp needle, it pops and produce a great sound. But, It doesn't pop when we open the mouth of the balloon (through which we have blown air)... So, Why doesn't the gas ...
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Did Felix Baumgartner produce a sonic boom during his jump?

I really got to thinking about this. The speed of sound is measured at 761.2 MPH at sea level. But how does this number change as air density decreases? The lack of air density is what allowed his ...
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306 views

How is sound produced at the atomic level?

How is sound produced looking from the atomic level? My thought process goes like this: Atoms are not perfect circles/solid spheres which we use to describe many macroscopic/classical phenomena.They ...
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1answer
11k views

Science behind the singing wine glass

A wine glass filled with water (approximately half or a quarter), when you use a wet finger and rub the top of the wine glass, the wine glass will produce a sound. I heard that it is because of the ...
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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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Microphones, Loudspeaker and their analogies to spring mass system

I have just started studying Microphones and Loudspeakers. I need a good text to refer which can explain their mechanical analogies with simplicity and basics too.
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Can we compute the magnitude of the stress caused by sound waves on a wall?

As a follow up to this question, Could we really compute the magnitude of the stress caused by sound waves on a wall? If so, How do we do that?
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Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
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Fundamental frequency , wavelength and the length?

What is the concept behind when it is said that for the first fundamental f=c/λ , λ should be equal to 2L . I have read the page http://en.wikipedia.org/wiki/Fundamental_frequency but I am still ...
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Eigen modes in a room

In a rectangular room 10*8*5 how can the eigen modes belonging to octave and third octave bands centered at 50Hz be found ? I have the formula to calculate the number of modes but don't have the idea ...
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366 views

Is it possible to hear the past?

From this Stack Exchange Physics Post, I am certain that it is possible to view the past. But then this interesting question came to me. Is it possible to hear the past? Ok, you might say, "Well, ...
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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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Does the human body have a resonant frequency? If so, how strong is it?

Inspired by this question on Music beta SE, I'm wondering if the human body has a strong resonant frequency. I guess the fact that it's largely a bag of jelly would add a lot of damping to the system, ...
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speed of sound and the potential energy of an ideal gas; Goldstein derivation

I am looking the derivation of the speed of sound in Goldstein's Classical Mechanics (sec. 11-3, pp. 356-358, 1st ed). In order to write down the Lagrangian, he needs the kinetic and potential ...
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Why does inverting a song have no influence?

I inverted the waveform of a given song and was wondering what will happen. The result is that it sounds the exact same way as before. I used Audacity and doublechecked if the wave-form really is ...
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516 views

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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Visualise the sound intensity

I'm studying Biophysics and my current subject is sound. One of the properties of sound is intensity. From my notes I can see the following definition: Intensity Formula is: $(I = w*m^{-2})$ or $(I = ...
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304 views

What does it mean to increase volume by X decibels?

I am trying to decipher what decibels are: http://en.wikipedia.org/wiki/Decibel It seems to be a log ratio of audio amplitude multiplied by a constant. I am confused by what this means though. If ...
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Why does a wobbly metal sheet make the sound of thunder?

In other words, what is the similarity between a lightning bolt and a wobbling sheet that make them sound alike? It seems to me that the two systems have a much different way of moving the air, and ...
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can sound travel is space?

Everybody knows that sound cant travel through space, but is really valid? Here is my scenerio: Given the size of a football field's length cubed, there are two objects at two opposing sides. the ...
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Why doesn't sound travel through walls?

If sound travels better through denser material, why does the sound travel better without a dense wall?
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Why does thermal resistance go down as temperature goes up?

Here is the thermal resistance data for three speaker coils disengaged from the speaker cone. Any ideas? I would think it would be a horizontal line. http://en.wikipedia.org/wiki/Thermal_resistance ...