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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The location of a point of destructive interference

Two speakers, one at the origin and the other facing it at x = 1.04 m, are driven by the same oscillator at a frequency of 642 Hz. If the speed of sound is 343 m/s, find the following. I know the ...
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26 views

Ratio of two RMS values in recorded audio

A quick(ish) question: I produce music and I am having a discussion on the difference between two RMS values in a specific record Nero: The Thrill (Porter Robinson Remix). In the verse, the RMS is ...
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7k views

Why doesn't light, which travels faster than sound, produce a sonic boom?

I know that when an object exceeds the speed of sound ($340$ m/s) a sonic boom is produced. Light which travels at $300,000,000$ m/s, much more than the speed of sound but doesn't produce a sonic ...
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23 views

How to calculate the radiation impedance of the horn loudspeaker?

The mouth of the horn is circular and there are many models in order to approximate the radiation impedance, such as: massless circular piston in an infinite baffle, unbaffled massless ...
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Any general method of determining changes in speed of sound with pressure?

I need to correct speed of sound measurements in various gases for changes in ambient pressure, typically 700-1100 mBar. Is there any general theoretical model available for this? Especially something ...
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51 views

Singing for physicists: How to resonate by body cavities with my voice?

My body has various cavities, such as my throat, mouth, chest, and nose. This cavities have resonant frequencies. I also have a voice box, which creates sound. How do I create sounds at the resonant ...
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18 views

Different noise when knock on a hollow wall

This might have a very simple answer, but I was wondering whether there was more to it. When we knock on a wall, the noise is different depending on whether there's a hollow space behind it or not. ...
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402 views

What are the rules for breaking a glass with your voice?

So, this morning I woke up and remembered something I discussed about with one of my friends: Can human voice really break a wine glass? So I looked it up and after checking many websites and ...
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35 views

Eqation between sound intensity and distance

For a project I'm trying to build a sound engine as realistic as possible and I am trying to add more features to enhance the sound localization. So far I've only implemented one of the three main ...
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1answer
33 views

Sound waves and chromism?

I am definitely not a physicist, but I have a question related to Physics so I thought I'd give it a try. Please excuse my ignorance. :) I am somewhat familiar with the changes in color caused by ...
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22 views

Is, in terms of sound, pouring water in a bottle the analogous of blowing into it?

When we pour some liquid in a closed container, for instance a jar or a bottle, we usually hear two (acoustical) noises: one is the classical turbulent (I guess white) noise, that in my view is ...
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43 views

Normalize Fourier Transform For Video Game [migrated]

I am in the process of developing a video game where I would like to sync a character's mouth with an audio clip of their speech that is playing. I found this great website that shows the profiles of ...
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1answer
31 views

Is it possible to “pull” sound waves using only an object?

Say, for instance, I am outside standing 20 feet away from a speaker. Is there an object I can put on my body that would allow me to feel the bass of the music more, without picking up the vibrations ...
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1answer
23 views

Frequency response of a capstan-like mechanical amplifier

Tension on a wire can be amplified by wrapping the wire around a powered rotating capstan, with output force governed by the linear capstan equation, Tout = Tin * emu*theta. Will this equation hold ...
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1answer
22 views

Reflection of Sound wave (Pressure Wave)

I want to study about the phenomenon of reflection of pressure waves as in an open ended organ pipe. Please suggest a suitable resource? I know about the harmonics in a stretched string and I can use ...
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1answer
30 views

Is it possible to send modulated ultrasound wave from underwater to air?

Is it possible to send modulated ultrasound wave from underwater to air? In case of radio frequency it is refraction loss at the surface between water and air. Is it something similar for ultrasound ...
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39 views

Why do thuds occur?

thud (noun): a dull, heavy sound, such as that made by an object falling to the ground. thud(verb): move, fall, or strike something with a dull, heavy sound. I'm not doing neither in the ...
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Physics of how the cochlea isolates frequencies along its length?

Can anyone explain the separation of frequencies along the basilar membrane of the cochlea please? (equations would be nice) I understand it being related to the resistance caused by fluid in the ...
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1answer
34 views

How can I easily measure the distance between well head and water surface continuously

Reprhasing the question is a more open ended manner: Method 1: Use a pipe and measure it's resonance. Given a closed pipe from 10 to 300 feet in length, and roughly 5/8" in diameter, made of 1/16" ...
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1answer
21 views

Maximum Penetration Depth for Ultrasound

How do you define the maximum penetration depth of an ultrasound? I'm assuming it means the depth at which the wave has attenuated to a certain small percentage of the original intensity of the ...
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7 views

What's the maximum pressure from an airborne ultrasound transducer?

I'm looking at haptic feedback as an area of research. It's cool because you can "hold" a strawberry or feel a virtual worm crawling on your hand. Here's a video demonstration. ...
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A level 9702/11/o/n/14 question 26 (about interference of sound wave) [closed]

The speakers are identical and they are connected it's series with power, so I thought there would be complete destructive interference. Therefore, at some point the amplitude would be zero and also ...
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1answer
24 views

What is the source of energy in this system? (resonance realated)

This is curiosity question, sorry if description is too vague. Suppose we have a string attached to some small frame on both sides Then we apply a force by plucking it with a finger, lets say 5.0 N ...
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1answer
31 views

How can I decrease the volume of a sound wave?

I have a sound wave in a computer, represented as a series of values (samples). Each sample is in the range roughly between -30000 and 30000. Say I want to decrease the loudness of the entire wave by ...
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2answers
24 views

How can I add two sound waves without reaching distortion - always keep them under a certain value?

I'm working on a program that adds sound waves on top of each other. I read that the best way to do that (correct me if I'm wrong) is to simply add them together. However, this way I easily reach ...
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1answer
39 views

How can I add a sound wave on top of an existing one, without harming the original's loudness?

I'm working on a program that has to do with adding sound waves on top of sound waves. Currently what I'm doing is simply an average of the two waves. So if I have wave ...
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158 views

Where do sound waves go after being heard?

I honestly can't come up with anything that makes sense, because obviously, energy cannot be created nor destroyed. I think the question is pretty self-explanatory, so there isn't much to say here.
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can a really loud sound travel in space?

I heard in a discovery news video that there is one particle every cubic cm in space. So, if i were to vibrate a circularbody of say mass 10000000kg at 10000000000000000000000Khz, would i be able to ...
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Could I break the sound barrier using circular motion? (And potentially create a sonic boom?)

Ok, Lets say I get out my household vaccum cleaner, the typical RPM for a dyson vaccum cleaner reachers 104K RPM, Or 1.733K RPS. In theory, this disc would be travelling with a time period of ...
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9 views

Efficiency of a resonant piezo-electric transducer in air

Anyone have ballpark figures for the typical efficiency of piezo transducers in air at low ultrasonic frequencies eg 100kHz? I'm looking for energy in versus sonic energy out.
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3answers
91 views

Why does the human body feel loud music?

I was sitting close to a speaker and I could feel the sound coming from it all over my body, especially in my heart, and it pounded with the loud beats of the music. Was my heart pounding because of ...
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14 views

Are partially deaf people able to determine where sound comes from? [migrated]

As in they can only hear with one ear. Time and level diferences between the two ears are only part of how the human body can localize the source of the sound. So what other factors are there and are ...
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13 views

speed of sound and ultrasound machine

How can you determine the speed of sound of a liquid using a medical ultrasound probe? I am unable to get a hold of a hydrophone. Is it possible to determine C using a or m mode?
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Frequency resonance of Bones, and other parts of the human body [duplicate]

Today in class we were learning about states of matter. I found out that in a solid the atoms are vibrating. This caused me to think about how crystal glass will break if an opera singer sings high ...
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Does a sonic pulse in a gas enhance thermal mixing?

I have a sonic pulse consisting of around 10 cycles that is propagated longitudinally through a gas in a tube. If there are thermal differentials in the gas (say between case and central portion of ...
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41 views

If I accelerate a mass quickly enough through a short distance (i.e. unit step function), would I create wind, sound, and heat?

As far as I know, the movement of air molecules can result in what we call wind, sound, or heat (and maybe some other things I'm not thinking of), depending on the assumptions about its motion. Wind ...
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Bell in a vacuum, where does the sound energy go?

I'm not educated in physics, but I learned that a bell struck in a small vacuum chamber will not be heard by people around it (in a school science lab). If it had been surrounded by air, there would ...
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1answer
62 views

different liquid in a container produce different sound

Does the type of liquid in a container affect the sound it produces? example like milk, water and coffee produce a minute different sound
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1answer
25 views

Is it realistic for soundwaves under water to “sink” or “float”?

I'm studying soundwaves under water and I had a numerical problem that I was asking about. http://stackoverflow.com/questions/28904017/are-my-matlab-iterations-working Now I wonder if you can tell ...
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1answer
28 views

Combining sound absorption coefficients

I am trying to predict the reverberation time in a room with different surfaces and different absorption coefficients (i.e. curtains, wood panels, carpet etc). My question is about how to calculate ...
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1answer
54 views

Why does my shirt make a crackling noise when it is static?

I thought that when clothing becomes "static" (used as a colloquial adjective for that state when clothing fresh out of the drier sticks to everything) it's because of a build up of electrons. That's ...
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2answers
59 views

The Frequency of a Trill

My music teacher recently pointed out to me that, when performing a trill (alternating between two notes very quickly) the finger for the higher note should be placed slightly lower on the string than ...
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1answer
22 views

What frequencies will get lost/diminished when you listen to a colloidal speaker without the backside

I was checking the connections of my colloidal speakers, so I had to listen to music without the backside of the speakers. There was clearly a difference in the quality of the music, but I couldn't ...
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2answers
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What is the exact physics behind sonic levitation

Me and a group of friends decided to choose sonic levitation as our research topic. However, after looking up the theoretical background, we hit a roadblock: (Here is an image of a standing sound ...
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1answer
33 views

Can ultrasonic signal be guided through a tube?

I have an industrial application using an ultrasonic sensor to detect whether transparent film is present in a plastic ring. Ring minimum diameter is > 30mm. Sensing distance is 90mm. Sensor ...
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2answers
53 views

What's the relationship between sound speed and acoustic phonons?

In the textbook, it says that the slope of the acoustic branch of phonons equals to the sound speed. There are 3 kinds of acoustic phonons including TA and LA phonons. Does it mean that there are also ...
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2answers
30 views

A simple question about frequencies, vibrations and engineering

I am a composer that likes science a lot but I am less than amateur at it. I am trying to start understanding how low frequencies (below 100hz let's say) behave. The intent is to find solutions to ...
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49 views

Special Relativity & QuickSilver from X-Men

In the movie X-Men: Days of Future Past, the mutant character Quicksilver possesses the ability to move very fast. A particularly memorable scene in the movie is one where he runs around very quickly ...
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absorption and reflection of sound on molecular level

Can someone explain the reflection and absorption of sound on the molecular level? What really is reflection? Why porous and soft material absorbs sound? What's the definition of soft in terms of ...
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Evolution of normal of material surface moving at a steady velocity

I need some help with the following question: A material surface moves with the fluid with a steady velocity $\mathbf{U_{o}}$. Show that the unit normal $\mathbf{n}$ to the surface evolves according ...