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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Can I compute the mass of a coin based on the sound of its fall?

Other day, I bumped my bookshelf and a coin fell down. This gave me an idea. Is it possible to compute the mass of a coin, based on the sound emitted when it falls? I think that there should be a ...
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how do compression and expansion of air transfer energy(sound) and why it is adiabatic not isothermal?

Suppose a vibrating fork exerts force to the air particles to compress which leads to the increase of internal energy (heat).This heat or energy given by the fork is given to the next layer of air and ...
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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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Do low frequency sounds really carry longer distances?

It is a common belief that low frequencies travel longer distances. Indeed, the bass is really what you hear when the neighbor plays his HiFi loud (Woom Woom). Try asking people around, a lot of them ...
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What are those characteristics by which every sound can be identified uniquely?

I have very basic question regarding sound I tried to search it over google but couldn’t find the right answer, my question: ...
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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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Does the Sun produce audible sound?

Theoretically if I were able to build some sort of device that let me sit 1 foot away from the surface of the Sun (or any star for that matter) without being vaporized, would a star produce any sort ...
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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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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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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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What is the minimum pressure of a medium for which a sound wave can exist?

At what pressure will be particles in a medium be unable to form a sound wave when disturbed? How can this pressure be described mathematically? My guess is that this would correspond to the point at ...
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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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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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Why do power lines buzz?

When near high tension power lines, particularly after a good rain, the lines themselves emit a buzzing noise. A similar noise can be heard coming out of the electric meters attached to my apartment. ...
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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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Why doesn't more light bounce off of things in the manner of sound?

If I'm sitting in the den with my door slightly cracked, I can hear my wife washing dishes in the kitchen down the hall. But why can't I also 'see' images of her washing dishes if, say, I looked up on ...
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Why do bass tones travel through walls?

I was in the shower while my roommate was listening to music and got to thinking about the fact that I could only hear the bass and lower drums through the walls. Why is this? The two possibilities I ...
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Why is the decibel scale logarithmic?

Could someone explain in simple terms (let's say, limited to a high school calculus vocabulary) why decibels are measured on a logarithmic scale? (This isn't homework, just good old fashioned ...
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596 views

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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Does a second similar source of white noise increase the overall noise level?

If I put next to my cooler another similar cooler that produces similar white noise, will the overall noise level increase? I want to point out that I am speaking about adding another independent, ...
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1answer
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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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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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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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How does gravity affect sound waves?

Someone asked me this question and I don't think I gave him an adequate answer (I was trying to think of the extreme case - that of neutron stars)
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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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678 views

Can someone explain how water from a garden hose can propagate in a sine/cosine wave?

A video posted on Youtube. How does this phenomenon work? I know he is using frequency to propagate water in a sine/cosine wave, but how does it exactly work this way? Why do we see it as if its ...
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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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If the source of sound is vibration, why can't we “hear” a object whose molecules are vibrating?

According to our physics textbook, the source of sound is vibration. According to our chemistry textbook, substances in solid state have molecules vibrating in a fixed position. So why can't I hear my ...
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221 views

Steel rod to Mars vs the speed of sound, how is supersonic travel possible?

I remember reading this passage in the "Feynman Lectures", where Dr. Feynman describes an experiment in which a theoretical metal rod of length equal to the distance between Mars and Earth is arranged ...
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1answer
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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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382 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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Why don't two musical instruments sometimes generate destructive interference?

I'm an electrical engineer, and I understand wave propagation, interference patterns, and so on. But I'm missing something basic, so perhaps my understanding isn't as good as I believe. I'll show my ...
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How much air needs to be displaced to generate an audible sound?

I'm reading a book where in one scene a wizard/alchemist teleports a scroll after reading. He folded the parchment carefully and muttered a single cantrip. The note vanished with a small plop of ...
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Why can't you hear music well over a telephone line?

Why can't you hear music well well over a telephone line? I was asked this question in an interview for a university study placement and I unfortunately had no idea. I was given the hint that the ...
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How does a steady wind flow generate sound?

When a wind blow through sharp edge, say, edge of a paper, you can see the vibration of the paper and hear the sound. For this type of oscillation, it should be a damped oscillation with external ...
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Physics of weird “boing” sound in racquetball courts?

While playing racquetball, I frequently hear a very prominent "boing" sound (or more formally, a chirp). For example, you can hear it in this video when the ball hits the front wall. Does anyone know ...
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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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Why sound does not heat up the air?

Both thermal energy and air are propagated through vibration of particles so why sound does not heat up the air e.g loud musical instrument does not generate much heat ?
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Theory behind patterns formed on Chladni plates?

In this video of vibrating Chladni plates we can see small sand particles align themselves into different interesting patterns (also shown in the image below) which correspond to some particular ...
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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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Why do bubbles make a sound?

I have an understanding of how bubbles work. They encapsulate air (or other fluids) in a membrane caused by surface tension. When they pop, there is often a sound. Sound is a type of energy, kinetic ...
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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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0answers
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Nonsensical dispersion relations for elastic wave propagation

In an earlier question about Einstein notation, a link was provided to a medical paper which used acoustic propagation to noninvasively detect the orientation of muscle fibers. In short, muscle fibers ...
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1answer
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Speed of sound and Break the sound barrier

What happens when plane exceeds the speed of sound? and What is the interpretation of the conical shape that appears behind the plane?
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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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1answer
676 views

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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587 views

How do traveling waves pass through a standing wave node, if the node doesn't move?

I'm having trouble with the explanation that a standing wave in a string is the superposition of traveling waves. The nodes in the diagram above are points where the particles of the string's ...
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5answers
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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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Why does a container with fluid make different sounds at different fluid levels?

Have you ever noticed that when you are filling a container with fluid. As it approaches the top, it makes a different sound? You can tell by listening when your about to reach the top. Why is this?