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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Why does sound absorption in oceans depend on the pH?

I was reading "The Sixth Extinction: An Unnatural History", by Elizabeth Kolbert, and there she comments that high level of $CO_{2}$ in the atmosphere lowers the pH of oceans (which makes sense) and, ...
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25 views

Beats: frequency of resulting wave vs. beat frequency

The beats frequency heard from the interference of two sound waves with frequencies $f_1$ and $f_2$ is $$\nu=|f_1-f_2|$$ Nevertheless the frequency of the resulting wave is not $\nu$ but the mean ...
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28 views

What enclosed geometry amplifies sound the most?

I am going to build a record player. It will read sound electronically but I also want it to be able to project sound mechanically, like a classic record player. So if sound enters a tube, can you ...
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13 views

How to Calculate Sound Pressure Levels using Microphone Sensitivity Rating

This is sort of a cross between a computer science and Physics question, but I would be grateful if anyone here could help me. My objective is to calculate the sound pressure level (in dB) of a ...
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105 views

Significance of wave number?

Till now all I know about the wave number is its formula i.e. ${\frac{2\pi}{\lambda}}$. I always wanted to know what it really means. So can anyone please, explain me its physical significance?
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25 views

Sound waves - physics [on hold]

A closed organ pipe of length L is in resonance with tuning fork. If a hole is made at a distance L/4 from the closed end will there be resonance again? If so when?
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18 views

How do I create a new voice out of multiple sources [on hold]

Hey guys, If 50 people with different accents read the same sentences in same tempo and I would record it. Could I create a new voice and accent based on all the recordings? How would the process ...
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3answers
52 views

Can sound travel in the form of transverse waves?

We all know that sound is a longitudinal wave but in some books, I have found that sound travels in the form of both longitudinal and transverse waves while passing through rocks. Can anybody explain ...
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3answers
503 views

Is there any effect on mechanical waves by electromagnetic waves (and vise versa)?

Do electromagnetic waves like light and gravitational waves (due to moon for instance) affect on mechanical waves like sound? Can sound change the path of light?
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133 views

Why do we hear better during the night? [duplicate]

At night, we hear weak and far sounds approximately clear, while during the day we cannot. My high school physics teacher was saying that “this is because of interference of sound waves. During the ...
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1answer
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Why do you only hear the bass when someone nearby is wearing earphones?

When someone nearby is listening to music through earphones or headphones, usually you can only hear the bass (unless it's really loud where you can hear the singer's voice and the other instruments ...
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39 views

Speed of sound in solid — temperature dependence

Let $v$ denote the speed of sound in a fixed solid, at a fixed temperature $T$. This will depend on properties of the solid (such as the bulk modulus and density). Given an increase in $T$, does $v$ ...
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27 views

What's the effect called when vibrations move through a cable under tension?

I'm not sure how to describe it, but there is a certain sound of vibrations through a tensioned cable, you might hear it as sound effects in a movie where cables are snapping, some have described it ...
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16 views

What happens when sound source is radiating through a hole in a cavity?

What happens to the external sound field , when loudspeaker attached to one wall is radiating inside a box and other wall has a aperture size of a diaphragm? Do we experience Helmholtz effect?
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30 views

Water in glass tubes producing different pitches when tapped. Why exactly is this?

So I've been making a DIY instrument for my physics project at school. I decided to try this experiment where I put different volumes of water into a glass cup, and I tap it with a spoon to create ...
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2answers
50 views

What is the difference between real value and abs value? [closed]

I am confused here, though I have been reading about it for years. What is the difference between a real value and an absolute value? For example, when do we take the absolute value of pressure or the ...
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58 views

Why do we hear a different timbre when someone speaks with helium (or other gases) in their lungs?

Let me make one thing clear: I am fully aware that the change in timbre comes from the change in acoustic wave speed when going through a different medium (just like light). However, would I not ...
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64 views

Percent variation of a physical quantity: how to choose who is in the denominator?

I came up with a very basic doubt on percent variation of a physical quantity,say $f$, defined as $$\delta f_{\%}=|{\frac{\Delta f}{f}}|\cdot 100$$ The problem is with the denominator. I'll make a ...
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17 views

Impulse response of air

Has someone captured impulse response of air with as few reflections as possible? It is said that high frequencies are diminished as sound travels, but I haven't seen any actual results of how say, ...
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1answer
31 views

Why do certain materials of nature ring when struck?

There are a wide range of elements and natural materials that will give off a ringing sound based on the material and the profile of the object is correct, most first think of metals ring best because ...
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3answers
50 views

Why do we add intensities for coherent sound sources?

When there are N coherent sound sources playing the same note at equal loudness, their sound waves add up to make a sine wave of the same frequency but most likely different amplitude (can be anything ...
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23 views

Seeing vs hearing a wave [duplicate]

Two questions came to my mind after reading the 4th para of the 1st answer of this question... Although we can't hear a 35Hz wave, can we see the object vibrating? Is there a range of ...
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1answer
24 views

how sound quantity in a period of time is measured by? [closed]

Let's suppose that I'm singing for 10 minutes and I obviusly produce some sounds, and let's imagine that I hold an instrument for measuring the amount of sounds produced within that period of time. I'...
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3answers
133 views

'Slapping' sound when trains pass each other

I have noticed that when riding in a train travelling at over 100 kmh$^{-1}$, a loud 'slap' can be heard when another train travelling at a similar speed passes in the opposite direction, followed by '...
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2answers
104 views

Why does a rolling thunder always starts with a high pitch and ends with a deep, low sound? [duplicate]

Rolling thunders always come cracking in with a high frequency, and the sound grows more deep as the rolling advances, ending with the deep sound of a roaring lion. Why? This is not the same question ...
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1answer
54 views

How to counteract Doppler's effect? [closed]

I am working on a robot in which I am detecting obstacles on sides using Ultrasonic transducers. Now the problem is, the target speed for the robot is 8.5 m/s and at this speed, the doppler's effect ...
3
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1answer
61 views

Sonic boom breaking glass

It's a well known fact that a sonic boom from something such as concord can shatter glass. I'm interested to know why a human is seemingly fine in the presence of the shockwave and yet the glass is ...
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41 views

How are sound waves of different speeds heard differently?

Lets say that there are two waves. They are both identical in every way except that one is traveling through a gas and another through a liquid. As we know they are traveling at different speeds and ...
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60 views

why cannot longitudinal waves travel through space (vacuum)

'The reason sound can't travel through a vacuum is that sound needs a medium (solid, liquid or gas with real vibrating molecules) and not because it is a longitudinal wave' How does this make sense as ...
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2answers
20 views

What do echo and reverbation have in common?

What do echo and reverbation have in common? They are the reflection of sound waves, they are formed when sound waves meet a hard surface, they cause a repetition of the sound. The waves keep having ...
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37 views

Why does scratching a blackboard gives such a painful noise?

I think we all have heard that terrible sound coming from scratching a blackboard with your nails. How is it produced? Has it something to do with the length of our nails?
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1answer
71 views

Time it would take for sound to travel between moon and earth? [duplicate]

Neil degrasse Tysons documentary series the Cosmos, he mentions that we actually see the moon one second later than it actually is due to the distance of the earth and the moon and speed of light ...
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1answer
34 views

Solution of Burgers' equation in preshock region

According to Hamilton's & Blackstock's Nonlinear acoustics (Section 4.5.4) the solution of Burgers' equation of the form: $$ \frac{\partial P}{\partial \sigma} - \frac{1}{\Gamma}\frac{\partial^2 ...
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1answer
22 views

How can the amplitude of the same acoustic wave be different in a interferometer?

I came up with an exercise on Halliday Resnick Krane that asked a question which consfuses me. I premit that I do not look for a solution of the exercise but for suggestions only regarding the ...
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1answer
37 views

Speed of sound in different states

Consider a gas at very low temperature(lower than critical) and pressure . Upon increasing pressure it will transform to liquid state. I know that speed of sound is independent of pressure, and also ...
3
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32 views

Doppler shift and Galilean relativity

Doppler shift has different forms if the observer or the source are in motion. I consider Doppler shift in the case of sound. I tried to find an answer on the non symmetry of Doppler effect, ...
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2answers
100 views

Acoustic beats interference vs. path difference interference

I'm trying to understand the differences between two kinds of waves interference. The first one is a time-interference, only due to frequency difference of the two waves with the same amplitude, which ...
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1answer
64 views

Effect of motion of medium on frequency

Will the frequency observed by a stationary observer will remain same if only the medium between the source and observer is moving?(ie. both source and observer are at rest and wind is blowing from ...
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37 views

Can I measure the mode shape frequency of a metal frame with a sound meter

If I 'ping' a metal frame it will resonate in many different mode shapes with different frequencies. I can see those shapes by doing a modal FEA analysis. When I use a sound meter to measure the ...
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19 views

How to convert from overtone to harmonics and vice versa?

I was given this question: If the pipe length in a tube is 1.9 m, at the air temperature inside the tube is 28 °C, determine the fundamental frequency of the note played, fourth harmonic and the ...
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64 views

How can I prove that antinodes are present at both open ends of organ pipe mathematically?

I know that for anti node to be formed the magnitude of displacement should be maximum at there. For standing waves in an organ pipe, the boundary conditions are such that anti nodes are formed at ...
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1answer
37 views

Subtracting Audio from a Song with Multiple Forms

This question may start oozing into the realm of copyright infringement, but let's discuss the theory first and foremost. I have a song with vocal and orchestral accompaniment from a well-known movie ...
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49 views

What is the max frequency of sound in a given medium?

When talking about acoustic waves, medium continuity (pressure, density) is implicit. But can the wavelength of an acoustic wave be as small as intermolecular separation? For example, can ~10 THz ...
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2answers
46 views

Speed of Sound in matter

So basically when it comes to the speed of sound, it is said that speed of sound in media is based on two main factors - 1)elasticity and 2)density from the formula V= $\sqrt{E/\rho }$ where E is ...
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3answers
69 views

What does a sound of infinite Hz sound like?

Say an airplane flies at Mach 1. The doppler effect causes the front of the sound emitted by the plane to reach infinite frequency: $f = \left ( \frac {343+0}{343-343} \right ) f_0 = ∞$ If the ...
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19 views

How to create planar acoustic waves?

The only way I can think of for creating planar acoustic waves is using a 2D phased array of transmitters, but even then the planar wave is not so planar (depends on the interference pattern, which ...
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1answer
30 views

How to measure dB in terms of factor?

We know that, 3 dB means factor of 2. 10 dB means factor of 10. By using this information, I want to calculate 1 dB to 10 dB in terms of factor. What could be the approach? Till now, my ...
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287 views

Why does the length of a wind instrument affect it's pitch?

I understand how length of a string on any string instrument affects it's pitch, but I don't understand how a short wind instrument produces a high pitch.
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why doesn't pitch or volume change the speed of sound? [closed]

If sound is a propagated by particles hitting each other in a tranverse wave, why doesn't pitch affect the speed of sound? Since frequency is the speed at which the particles hit in a period of time, ...
8
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Pressure standing wave nodes at the end of the open side of a tube

I do not understand why standing sound waves can be formed in a one-side or two-side open tube. Consider a one-side open tube. In particular how does the reflection of the wave at the open end occur? ...