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)

0
votes
0answers
18 views

Bass and acute tones. Perceiving their direction

In a modern sound system, you put the sub-woofer somewhere on the floor, not worrying much about its position, but putting the loud speaker around my ears, to generate a sound-surround effect. I ...
1
vote
1answer
56 views

How to calculate frequency in the following question [closed]

A police car with a siren of frequency $8$ kHz is moving with uniform velocity $36 \mathrm{km}\, \mathrm{hr}^{-1}$ towards a tall building which reflects the sound waves. The speed of sound in air is ...
1
vote
1answer
41 views

Could one estimate the size of air-molecules based on analysis of the sound?

Say one knows air is composed of molecules (atoms). Could one estimate the size of molecules (atoms) by analysing the sound properties as one perceives them (clearness, speed, etc.)?
10
votes
4answers
892 views

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 ...
0
votes
1answer
97 views

Help w/ speed of sound experiment report question

Experiment was done by using an oscilloscope and a piezoelectric transducer to generate ultrasonic sound waves. We had to move the transmitter whilst receiver remains constant on a angled 1 meter ...
2
votes
1answer
277 views

What is sympathetic resonance?

When two tuning forks stand near one another and one is excited, the other rings as well. When high notes are struck on a piano, lower notes are also heard. If I understand correctly, this is called ...
4
votes
1answer
117 views

Is there a max loud?

Take two laptops with build-in mics and speakers. Put them next to each other. Turn skype on both of them, and call each other. Laptop A should now be in a voip call with Laptop B. Talking into ...
2
votes
1answer
28 views

Perception of sound in varying temperature

If one disregards situations like explosions (where air is heated) etc. and also disregards humidity – does temperature affect sound in any way for the observer? Say for example one listens to a ...
2
votes
1answer
70 views

How are complex sound waves combined?

Audio is often explained by single frequencies. Typically this is a sound wave: plot sin(x) * 2 from 0 to 10 However we usually deal with more complex sounds, ...
7
votes
6answers
590 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 ...
1
vote
1answer
47 views

What can you use voice sound for? [closed]

Moreover, how can you make your voice productive? for example, using it to light an LED, charge a battery, purificating water, growing plants in a more efficient way. I want to do a project that ...
2
votes
1answer
63 views

Interference - the shortest way from the point of constructive one to the point of destructive one

So this is a problem from Polish maturity exam. The image shows 2 speakers (G1, G2) and point B. The wavelength of sound coming from both speakers is 0.155 m, and the wave coming from both speakers ...
1
vote
2answers
77 views

What does a constant signal sound like?

Say I was sampling a sound incorrectly and it produced a constant signal as below: What would this signal sound like? In Matlab, it plays nothing. Is this correct?
11
votes
2answers
247 views

How loud is the thermal motion of air molecules?

In other words, given a magical room with walls that produce no vibration and transmit zero vibration from the outside, and nothing on the inside except room temperature air, what would be the noise ...
-1
votes
1answer
162 views

Relation between pressure and particle displacement in an acoustic wave

Consider an acoustic wave in some medium, expressed as particle displacement: $$s(t,x) = e^{j(-\omega t + kx)} $$ I understand that pressure must be at its maximum when the particle displacement is ...
1
vote
1answer
56 views

Can the motion of a cracking whip be described as the interference of two waves?

I was watching a whip crack in slow motion and I noticed that the motion of the whip could be described using two different circular descriptions. 1) the user circles the whip around over his head, ...
1
vote
1answer
56 views

Does sound gets faster when air bubble is supend in water?

Does sound gets faster when air bubble is suspend in water? c = sqrt(K/P) c = speed K = bulk module P = density When air bubbles is homogenized into water the density is lower, so should sound ...
2
votes
2answers
148 views

Is work done by sound wave on air particles?

Is it possible for sound wave to do net work on air particles? As in can a sound wave make the air move in one direction so that it can for example move a sail boat ? I think since molecules gyrate ...
1
vote
0answers
44 views

What is the physical origin of acoustic modes in a duct?

Lets deal with wave propagation in a cylindrical duct. We ask the question: "what is the general form of a pressure wave which can propagate through the duct?" In answering this, we assume that the ...
0
votes
3answers
64 views

How does ultrasonic horn produce a convection current in the water?

When I was using ultrasonic horn in a beaker, I notice that there are convection currents in the beaker and stir up my substance. I don't understand why it produce water current, I thought that it ...
2
votes
2answers
78 views

What is the difference between a puff of air and a sound wave regarding creation and propagation?

While watching a Schlieren video of a hand clapping, I noted a very distinct difference between a sound wave and a puff of air, which were both created by a hand clapping. What is the difference ...
2
votes
1answer
107 views

Does timbre consist in pitch and volume?

I read that the physical properties of a sound wave correspond to its audible qualities: pitch, volume, and timbre. However, an oscilloscope uses only two-dimensions to accurately depict the physical ...
3
votes
2answers
113 views

How to model “Doppler Distortion” of speakers?

Simple Model w/o Doppler I have a speaker driven by an electrical signal. The pressure at the sampling point is some linear operator acting on the input signal: $L[ s(t)]$. Where $L$ combines the ...
4
votes
2answers
444 views

Frequency of touch, taste, and scent [closed]

So I was thinking about sound - and how anything below 20Hz is basically inaudible to humans (because it is too low of a frequency to be recognized), as well as anything above around 20KHz (because it ...
4
votes
2answers
155 views

Why are two voices singing the same note louder than one?

Let's say for example: Two people sing the same note (frequency) and volume (amplitude) together. Why is it that the two persons sound louder than they would ...
2
votes
3answers
218 views

Would we be able to hear the sun if space were full of air? [duplicate]

I was wondering if the sun could be audible from earth in an air-filled space scenario. We can ignore all the other disastrous consequences! Thanks!
0
votes
1answer
90 views

Does sound absorption depends upon the amplitude of sound wave?

I can understand the mechanism of frequency dependant sound absorption by most materials but does the sound attenuation also depends upon the AMPLITUDE(sound pressure or rather loudness/sound ...
0
votes
2answers
106 views

Do Pulsar Stars produce sound?

Can I hear electromagnetic radiation coming from a pulsar star? Or can I hear it if I stand outside it?
3
votes
2answers
154 views

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 ...
1
vote
0answers
73 views

Number of wave modes in a cavity

I'm trying to calculate the number of acoustic modes that can exist in a room in a certain range of frequencies. I thought of using the Rayleigh-Jeans formula for the electromagnetic standing wave ...
0
votes
0answers
57 views

What physical properties of silver would contribute to the sound of a musical instrument?

Sorry if this is off-topic. A question was recently asked on Musical Practice & Performance, asking what physical properties of silver would contribute to the sound of percussion instruments. It ...
7
votes
1answer
309 views

Are small speakers inherently limited to higher frequencies?

I am hoping to build a subwoofer using multiple smaller speakers (165mm) instead of a single larger speaker (380mm). My theory is that the displaced air volume is what matters, not the individual ...
2
votes
3answers
149 views

Are there any musical instruments which use resonance tubes with two closed ends?

Many musical instruments use resonance tubes with one closed end - all brass instruments (I think), clarinet, etc. There are also instruments where both ends are open (flute, pipes) Are there any ...
1
vote
0answers
58 views

Why do the chargers produce persistent high pitch sound?

I have noticed that my Nexus Orb charger and a charger for the shaver produce some unpleasant high pitch sounds - near the fork. Why are they doing this? Does it indicate any problem with my ...
3
votes
2answers
68 views

About our voice transferred into electrical signal

I know when we speak to the microphone, the pitch of our voice cause the vibration of magnet in the microphone, thus causing generation of different voltages of electrical signal. But my question is: ...
1
vote
2answers
156 views

Why does a microphone membrane only measure pressure and not particle velocity?

Microphones (e.g. condenser microphone) are assumed to have a voltage output proportional to the sound pressure at the diaphragm. If the operating principle is that the voltage output is proportional ...
0
votes
0answers
33 views

Justifying order of magnitude reasoning

So in the context of a set of notes I am reading about acoustics I get to equation (23) in this paper. Basically it comes down to showing that (note the dots above the a's meaning time derivative!) ...
2
votes
3answers
98 views

What is sound in terms of acoustic sources?

Sound is nothing more than small amplitude, unsteady pressure perturbations that propagate as a longitudinal wave from a region in space which created it (called the source region) into a quiescent ...
5
votes
2answers
150 views

Does vortex shedding exist along the surface of an object?

Vortex shedding occurs due to the detachment of flow. The typical example is for the oscillating wake behind a cylinder, and has a frequency related to the size of the object. I want to know, if a ...
2
votes
0answers
45 views

What is the longest distance over which echolocation is effective?

Some animals, most notably bats, use echolocation in order to navigate and detect the location and size of objects and prey. This usually takes place over short distances. What are the theoretical ...
1
vote
0answers
128 views

Harmonic frequencies of electric guitar are detuned. What could be the cause?

I have tried to record some music with my electric guitar and while playing around and looking the frequencies of single strings I noticed something strange. I took the spectra of the A string and I ...
38
votes
6answers
4k views

Without seeing the lightning, can you tell how far away it struck by how the thunder sounds?

Is there any way to tell how far away a lightning strike is by how its thunder sounds? I thought one way might be by using the fact that higher frequencies travel faster than lower frequencies. Would ...
1
vote
1answer
234 views

Will a sound composed of the frequencies 450Hz, 650Hz 850Hz have a clearly defined musical pitch? Why?

According to my lecturer, the perceived pitch of a sound composed of the following harmonics: 750Hz, 1000Hz, 1250Hz is equal to the fundamental frequency which is the highest common factor of the ...
31
votes
7answers
5k views

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 ...
1
vote
0answers
98 views

The sound when boiling water [duplicate]

One can hear some sounds when boiling water, and usually the sound is loud initially, then it becomes quieter. When the water is about to boil, the sound starts to be louder again. Also, one may ...
1
vote
2answers
118 views

Sound as a use to separate molecular structures

Sound can be a destructive force. However, could it be used to separate say the Hydrogen atom from the Oxygen atoms?
1
vote
1answer
56 views

Standing sound wave tube

If there was a standing sound wave tube and a flammable gas was introduced then ignited, would the combustion be more forceful and more efficient since its following a standing wave, than just a gas ...
2
votes
2answers
235 views

Why is sound intensity proportional to the square of sound pressure not to sound pressure alone?

I am trying to understand the physical principles behind the sound intensity and sound pressure. As far as i know, sound intensity is proportionate to the squared sound pressure. Can someone explain ...
0
votes
1answer
58 views

Finding the wavelength of acoustic source underwater [closed]

I am currently working on a data fit assignment for my class and ran into some confusion. I will post the entire question here so you can get some background but the only question I have is with ...
0
votes
1answer
54 views

If we hear a noise long enough, is it going to settle as tinnitus? [closed]

Some equipment sometimes have a high pitch ringing, and I was wondering out of curiosity: can noises (not only drive you crazy but also) settle and become permanent ringing in your ear if you are ...