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.

learn more… | top users | synonyms (1)

8
votes
2answers
996 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 ...
2
votes
2answers
148 views

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: ...
15
votes
4answers
2k views

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 ...
0
votes
0answers
123 views

Why it happen's when I rub my finger's? [duplicate]

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 ...
2
votes
1answer
367 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 ...
1
vote
1answer
123 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 ...
-1
votes
1answer
87 views

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) = ...
13
votes
2answers
5k views

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 ...
3
votes
2answers
337 views

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 ...
7
votes
3answers
2k views

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 ...
3
votes
1answer
4k 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 ...
0
votes
1answer
469 views

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 ...
2
votes
3answers
256 views

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 ...
10
votes
3answers
10k views

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 ...
3
votes
3answers
5k 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 ...
2
votes
1answer
736 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 ...
2
votes
2answers
2k 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?
3
votes
1answer
3k views

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 ...
3
votes
3answers
455 views

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 ...
1
vote
4answers
222 views

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, ...
82
votes
7answers
14k views

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 ...
0
votes
1answer
402 views

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 ...
33
votes
4answers
2k views

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 ...
2
votes
2answers
3k 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 ...
0
votes
1answer
41 views

How is the wattage of a human larynx calculated?

This site says the typical human voice has a wattage of about 1W. Another site indicates it is 80db with about 0.001W of energy. I'm confused. How does one compare 80db of 0.001W against 1W? Most ...
0
votes
1answer
608 views

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 ...
1
vote
3answers
549 views

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 ...
0
votes
1answer
501 views

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 ...
2
votes
1answer
1k 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 ...
1
vote
1answer
65 views

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 ...
3
votes
1answer
662 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 ...
3
votes
1answer
4k views

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 ...
2
votes
1answer
75 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 ...
2
votes
1answer
1k views

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 ...
1
vote
2answers
272 views

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 ...
0
votes
0answers
55 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?
1
vote
0answers
60 views

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 ...
5
votes
3answers
2k views

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. ...
8
votes
2answers
364 views

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 ...
6
votes
1answer
503 views

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 ...
5
votes
1answer
2k views

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 ...
0
votes
1answer
970 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 ...
0
votes
1answer
674 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.
11
votes
1answer
1k views

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 ...
4
votes
1answer
109 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 ...
3
votes
2answers
11k views

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 ...
1
vote
0answers
88 views

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 ...
14
votes
5answers
1k views

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 ...
8
votes
3answers
736 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 ...
2
votes
0answers
173 views

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 ...