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)

-2
votes
0answers
17 views

Levitation curiosity

I do not study physics so forgive me if this question sounds stupid to you but I was wondering since small objects can be levitated using acoustic levitation, can much larger objects be levitated with ...
2
votes
2answers
49 views

How can the choice of wood make a good violin?

We always hear about some really fine and expensive wood that is used to make guitars, violins and other musical instruments. What's the physics behind this? What parameters (e.g. bulk modulus etc.) ...
4
votes
1answer
141 views

Using a laser to overhear a room conversation

Movies with science based tricks and gimmicks are generally silly and sometimes even annoying. The science based trick that I don't know enough about to judge is the following (and I have seen it in a ...
4
votes
2answers
23 views

Refraction, diffraction or reflection of human voice

Why is possible to hear in an open space someone's voice even if he's not facing me? Is it because of refraction, diffraction or reflection of the sound wave?
0
votes
2answers
17 views

Does background noise while strumming a string affect the frequency recorded?

Does the interference of the waves cause instances of destructive interference where there is no amplitude. Technically the wave is still there although its amplitude is 'cancelled' out but those ...
0
votes
1answer
55 views

Do two waves of different frequencies create a resultant wave of lower frequency?

In my results for testing background noise, i found that while strumming a guitar in: a noisy area, the frequency picked up by the mic was 352 Hz while in a quiet area, the frequency picked up by ...
1
vote
2answers
21 views

Interference of two waves of different frequencies relevance to background noise + sonometer

If two sound waves of different frequencies are recorded then does the interference between the two waves of different frequencies alter the resultant frequency recorded. In better context, I'm ...
0
votes
1answer
21 views

Directional subwoofer?

I was thinking. The subwoofers that I've seen are a circular parabolic surface section (or perhaps a circular circlic(?) surface section?) and are considered omni directional. I would guess that ...
0
votes
0answers
28 views

Is there a version of “delayed choice” for sound waves?

I'm familiar with the uncertainty principle in harmonic analysis, which states that you can't localize the support of a function in both the time domain and the Fourier domain. One of the physical ...
3
votes
2answers
74 views

Why speaker beeps when a cellphone is kept near it?

Once I had kept my cellphone near a computer speaker. After some time, a call came over my phone. Strangely, the speaker started humming and beeping till I received it. Why did the speaker started ...
0
votes
1answer
12 views

Why would the acoustic absorption coefficient of hexane in air be less than air?

Why would the acoustic absorption coefficient of hexane in air be less than air? That is, a 120kHz pulse train shows a bigger amplitude after traveling in a hexane/air mix than in pure air? My ...
2
votes
1answer
34 views

Aerodynamic noise created by cooling fan

What is the reason behind the noise created by fan blades while moving? Some paper says that it is because of the Kármán vortex street but it can be formed in static bodies only. Most of the ...
0
votes
1answer
28 views

Is there a mathematical relation between the volume of a speaker diaphragm and the intensity of sound it produces?

I am trying to find out how speaker cones of different diaphragm volumes will produce a certain intensity of sound. Is there a relation that could be used after the volume of the cone has been found?
-1
votes
0answers
21 views

Find the diameter of the tube and frequency of resonance [closed]

A tube of a certain diameter and of length 48 cm is open at both ends. Its fundamental frequency of resonance is found to be 320 Hz. The velocity of sound in air is 320 m/sec. Estimate the diameter of ...
2
votes
0answers
30 views

Finger snapping: Maximum fingertip speed and generated pressure change

The wikipedia page for finger-snapping (or finger-clicking) describes the physics thus: There are three components to the snapping finger sound: (1) The "friction" or "sliding" sound between the ...
2
votes
2answers
75 views

Is it possible to measure temperature using sound?

Is it possible to measure the temperature of something using sound, by blasting sound waves at solid objects, liquids and gasses, then measuring how much sound is reflected or absorbed, to give an ...
3
votes
1answer
26 views

What is the Optimal Separation Length for the Tines of a Tuning Fork?

I'm building tuning forks (for fun... why not?), and among one of the design decisions is how far apart should I place the tines (the two long prongs) from each other. I'm not entirely certain whether ...
0
votes
0answers
20 views

Hearing sound when going supersonic

Suppose we are travelling supersonic along a straight line. Further up along the line, there is a stereo, that's emitting sound at a frequency that changes in such a way that the Doppler shift caused ...
1
vote
0answers
27 views

What is the relationship between the velocity of an object and its Sound Intensity Level in an inelastic collision?

Assuming the mass, acceleration, and height of the dropped object are constant and the area of the measured sound wave is constant, would the relation be linear, exponential, logarithmic, square root ...
0
votes
0answers
17 views

Why do acoustic lenses need air channels?

In every design of an acoustic lens I have seen so far, be it Fresnel lens or GRIN lens, there are always air channels included in the design. I don't see why this is needed. Couldn't a lens be built ...
26
votes
4answers
5k views

Is a bomb's shockwave strong enough to kill? [closed]

I'm watching a movie, The Hurt Locker, and the first scene shows an IED explosion which kills a soldier. Of course movies don't depict explosions with maximum realism, but I noticed the debris and ...
0
votes
3answers
36 views

Pitch range and size of wind instrument

Looking at wind instruments, there is an apparent relation between the size of the instrument and the pitches it can produce; The larger it is, the lower pitches it produces. The question I have is, ...
-1
votes
1answer
44 views

Reproducing electricity [closed]

We all know reproducing solar energy is possible. Same stands for mechanical energy (air, water, coals) - they are all reproducible. But what about other types of light ? A diode light for example ...
0
votes
0answers
23 views

Is there an acoustic Black Body Radiation?

Imagine a cavity in a infinitely extended solid filled with another type of solid in thermal equilibrium. Are there statistics for phonons equivalent to the Black Body Radiation by Planck?
1
vote
1answer
128 views

Why am I not hearing frequencies of range 14 kHz-15 kHz? [closed]

Recently, a Radio Station (Red FM, 93.5) started a campaign called "RED FM bajao Machar Bhagao" (English: Play RED FM, scare away mosquitoes). In this, they claim to be broadcasting some frequencies ...
1
vote
1answer
67 views

I made a tin can phone using a plastic slinky and paper cups. Why didn't it work?

After watching some videos on Khan academy in regards to the information theory, I spent a few minutes creating a primitive "tin can phone." The materials of my phone are a plastic slinky and two ...
5
votes
3answers
374 views

Why do magnets silence anvils?

Today I've been to a forge. The blacksmith demonstrated that if he beats the anvil without a magnet attached, it make horrible noises. As soon as he reattached it, the sound of the anvil was way more ...
0
votes
1answer
40 views

What are the proper unit types for the calculation of the frequency of a tuning fork? [closed]

Wikipedia Article on the subject The formula states that the calculation of the frequency with cylindrical tines should be $$1.875^2/(2\pi L^2)\times(Er^2 /(4P))^{1/2}$$ where the variables are ...
0
votes
1answer
40 views

Car window vibrating noise

I was going to ask a question similar to: Why, when one opens 1 car window, does that noise occur? but saw that it was already asked and answered very helpfully. However, there are a couple other ...
0
votes
1answer
85 views

What is causing the Trumpet Sounds that are emited from the sky?

In these last years, a phenomenon have appeared in several countries (US, Canada, Australia, Russia, Germany, and others). It consists of sounds like a trumpet coming from our own planet's sky. ...
1
vote
1answer
63 views

Can sound waves be made to project 3-D shapes, like a reverse sonar? [closed]

Can sound waves be manipulated to project 3-dimensional shapes or forms, like a reverse sonar?
1
vote
2answers
39 views

Why is it difficult to hear when speaking in the presence of strong wind?

We say that sound waves require medium for their propagation, but during heavy storms or strong wind we cannot hear sound properly. Even if wind is flowing towards specific direction and we speak in ...
1
vote
1answer
43 views

Drinking glass sound amplifier

It is often seen that drinking glasses are placed overturned on the walls for listening more clearly what is happening on the other side of the wall.What is the reason for this?Is the reason same for ...
0
votes
0answers
25 views

concerning the effects of temperature and density on the speed of sound [duplicate]

here is my relatively broad question: how does the temperature and density of a medium effect the speed at which sound travels through it? Now I shall elaborate: it is my understanding that there ...
0
votes
2answers
39 views

Two supersonic planes. Do they hear each others sonic boom?

Plane A is traveling at Mach 2 and is over taken by plane B traveling at Mach 3. Does plane A hear the sonic boom from plan B? If so when? Does plane B hear the sonic boom from the slower Plane A? ...
2
votes
3answers
493 views

Breaking the sound barrier underwater

Theoretically, if I were to launch something faster than the speed of sound in water (around 5 times that of air), what would happen?
-1
votes
1answer
21 views

what is the pressure that a sonic wave actually creates?

We know that sonic waves across atmosphere are basically areas of high and low pressure. But I couldn't find how much is that pressure. There are online calculators to calculate the sound pressure, ...
2
votes
0answers
36 views

Books about musical acoustics

Apart from physics, I love music and I want to learn about musical acoustics. I know some things, but the problem is that most of musical acoustics books are written for musicians. That means that ...
0
votes
2answers
40 views

what is the effect of a sound wave at the opposite side of its direction?

We know that a sound source produces a sound wave and a high pressure area is followed by a low pressure area, while they travel with 300m/s. My question is, if the sound source travels with 50m/s in ...
1
vote
3answers
48 views

can I move air masses with sound waves?

I know I can move air with a fan. Could I move air with sound waves. If yes, how exactly? would it be more efficient? What setup do I need?
3
votes
1answer
51 views

Mechanical waves with slower speed than sound

Sound is mechanical waves of high and low air pressure transmitting with 300m/s. Are there high and low air pressure waves transmitting with lower speeds? How are they produced?
1
vote
1answer
54 views

Does the Inverse Square Law apply for all frequencies of sound?

We often seem to only hear the lower beats of music far away, whilst the higher frequency sounds seem to diminish more quickly - remaining unheard. I know that sounds with higher frequency have ...
0
votes
0answers
36 views

Which is has the highest (greatest) sound intensity - Sine, Square or Sawtooth waveform?

From this, http://electronics.stackexchange.com/questions/42904/square-wave-sine-wave-is-more-audible I now understand that a Square soundwave will be perceived louder than that of a Sine sound wave ...
-1
votes
3answers
118 views

Relationship between the frequency and amplitude of wave

I wonder is there any relationship between frequency and amplitude of wave. Generally, most of the people say that frequency and amplitude are independent to each other. But in this case, where it is ...
0
votes
2answers
43 views

speed of sound in hydrogen vs. speed of sound in air

How much faster does sound travel in hydrogen with density 0.0896 g/L than in air with density 1.293 g/L at the same temperature and pressure? Is there any solution to solve this?
1
vote
1answer
71 views

Determine fan sound (dB) based on its rotational speed (RPM)

I am trying to find the sound amplitude or level produced by a fan, knowing its RPM. Is there a simple formula for it? What other parameters does it depend on? Assume I have all the fan properties, ...
14
votes
5answers
1k views

Why does medium not affect the frequency of sound?

I read in various places that frequency does not change with medium. Instead, wavelength changes in different mediums due to a change in speed. I understand why speed changes with medium, but I'm not ...
7
votes
3answers
128 views

Need mathematical explanation for different musical notes sound different on different instruments

I am not expert in music. There are number of musical instruments. One (especially a person who knows about music) can blindly recognize which instrument is being played just by listening to it. I ...
0
votes
0answers
17 views

How to assess the acoustic power gain of resonnators (openended waveguides and Helmholtz)

I'm looking for a way to link acoustic power gain and time delay to geometries for these kind of resonnators. The botttom idea would be to design and 3d print an acoustic guitar that does not rely on ...
1
vote
0answers
31 views

Can I measure distance with sound through soil?

Can you measure distance (cca. with precision 0.1m-1m) with sound through soil. I know this is really crazy think to do, but I have this idea quite for a while. Basically I will set speakers on fix ...