Questions tagged [acoustics]

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.

Filter by
Sorted by
Tagged with
0
votes
0answers
6 views

Synchronize clocks with speed of sound to measure one-way speed of light

If you use light to try and synchronize clocks to meassure the one-way speed of light it doesn't work, because if c is not constant in all directions, the clocks are not synchronized to beginn with ...
0
votes
0answers
12 views

How would a backward propagating sound wave behave in a roton producing metamaterial medium?

Phys.org link to paper: Roton producing metamaterials could theoretically make sound waves beyond certain wavelengths, propagate backwards. Does it mean reversed sound, or will it be able to traverse ...
0
votes
1answer
45 views

Would a simple experiment show that pressure transmits through water at the speed of sound?

Let say we have a 100 m long metal pipe with its two ends equally positioned at 1 m above the rest of the pipe. The ideal case would be a U-shaped pipe... The pipe is whole filled with water. Now, if ...
1
vote
1answer
30 views

Mach number at very high altitudes

The Mach number is defined as $$M = \frac{v_\infty}{a}$$ $v_\infty$ is the flow speed wrt the aircraft, and $a$ is the local speed of sound. For lower altitudes (within the troposphere) Mach number ...
0
votes
2answers
40 views

Can an object keep changing its Resonant Frequency?

I was studying Acoustic Resonance and Resonant Frequencies and learned a lot ... but I have a question which probably the web doesn't seem to answer! Can an object(any object)keep changing its ...
0
votes
2answers
36 views

Boundary conditions for the wave equation in spherical coordinates

Consider the wave equation (In this context, I'm talking about an acoustic wave), $$\frac{\partial^2 p'}{\partial t ^2} - c^{2} \nabla^2 p'=S.$$ Let us assume this is in free-space, i.e, there is no ...
1
vote
2answers
60 views

Why is a subwoofer bigger than a tweeter? [duplicate]

I came across this video - The Fundamentals of Sounds - where it says in 14:00: Subwoofer is larger because it needs to be bigger for those larger low frequency waves to propagate through and the ...
2
votes
1answer
60 views

Why speed of sound in gas depends on density but not pressure?

The book tells that with decrease in density there is an increase in speed of sound in gas but with increase in pressure there is no change in the speed of sound in gas. Why? If pressure increases ...
1
vote
1answer
55 views

How would a warp bubble interact with an atmosphere? [closed]

What would happen if a warp drive entered the Earth atmosphere? IIRC some scientists have created mathematical models that have shown that warp bubbles that don't exceed the speed of light may be ...
2
votes
2answers
36 views

Simplifying acoustic test procedure — don't want to bother neighbors with party!

I am having a party and would like to keep disturbing neighbors to a minimum, but maximize the volume we can get away with. I devised a quick n' dirty test plan to generate some frequency response ...
0
votes
2answers
36 views

School investigation: How does the size of a resonance box affect the sustain of a guitar string?

TL;DR for a lab report, how does the volume of a resonance chamber underneath the guitar string affect its sustain i.e. time it stays above a volume threshold x. Is there an equation to model this ...
0
votes
1answer
27 views

Speed of sound in a solid calculated theoretically

I am trying to find theoretically precise values of the speed of sound in various solid materials. I have found the CRC Handbook of Chemistry and Physics with a table of values with no uncertainties ...
3
votes
0answers
54 views

Why do I hear static when I plug in my earphones incorrectly?

I use simple earphones which are wired with my laptop. Most of the times I unconsciously plug them in without looking and at times instead of going in the port they touch the laptop body near the port ...
1
vote
1answer
55 views

Intuitive explanation for the second solution. Projectile problem [closed]

Take the classic problem of a person standing on a high building/cliff and throws an object which follows a parabolic path to the ground. Solving this problem gives two solutions for the time in which ...
3
votes
1answer
46 views

Change in refractive index due to the acousto-optic effect, and the use of acousto-optic modulators for the sole purpose of frequency shifting

Chapter 3 Acousto-Optics of the textbook Crystal Optics – Properties and Applications by Ashim Kumar Bain says the following: In general, acousto-optic effects are based on the change in the ...
0
votes
1answer
25 views

Local speed of sound in a perfect gas

I have some doubts regarding the derivation of the formula for the local speed of sound in a perfect gas. I am going to use the related wikipedia page as a blueprint to expose my doubts. We can show ...
0
votes
0answers
23 views

Calculating $\Delta V_{sound}$ when $\Delta T = 1 K$ when $v_{sound}$ at 273 K = 332 m/s

Here is my solution We know that $v_{\text{sound wave}} = \sqrt{\frac{\gamma RT}{\rho}}$ which means that $v_{\text{sound wave}}\propto T(\text{in Kelvin})$ $\implies \frac{v_1}{v_2} =\sqrt\frac{T_1}{...
1
vote
1answer
61 views

Why is the speed of sound constant in a medium?

Why is the speed of sound constant in a given medium? What is the intuitive picture behind it? Like for example, I would imagine that "hitting" the air "harder" would make sound ...
1
vote
0answers
9 views

Do acoustic waves in liquid crystals have transverse modes?

According to a previous question: Modes of propagation in media acoustic waves in media can be decomposed in two kinds of modes: longitudinal and transverse; solids being the only one where they are ...
0
votes
0answers
30 views

What would sand on a Chladni plate look like with a complex wave?

I'm doing a demonstration for students using a Chladni plate. My setup is similar to this one, https://www.youtube.com/watch?v=1yaqUI4b974 consisting of a single frequency-generator attached to an ...
2
votes
2answers
41 views

The lowest possible frequency of sound wave

What is the lowest possible frequency of sound waves. I imagine that if a plate vibrates slower and slower it stops producing sound and starts to just 'move' the air around. What is this minimum ...
0
votes
0answers
15 views

Acoustic resonance in pipe

This is quite a quick question. Would you call the acoustic resonance generated in pipes with a speaker to be caused by the pipe itself, or the speaker?
0
votes
1answer
22 views

Longitudal waves. Proof of $\Delta p=B \frac{\partial s}{\partial x}$

I have trouble understanding some derivations about longitudal waves. I need to derive $\Delta p=B \frac{\partial s}{\partial x}$ from $\Delta p=B \frac{\Delta V}{V}$ knowing that $\Delta V=A\Delta s $...
0
votes
1answer
50 views

What if speed of air exceeds 340m/s?

We know that Mach cones are formed when an object moves faster than the speed of sound. This creates huge noise in the surroundings. Here the airplane is moving faster than sound relative to ...
1
vote
1answer
35 views

Can we decompose sound like white light is decomposed (dispersed) in different colors?

When we send white light through a prism, the light is decomposed in the colors that constitute it due to the different velocities which different frequencies. Is there a way to decompose "white ...
0
votes
1answer
29 views

Does sound have any meaning in space?

Sound is just an disturbance of partial in a medium and every disturbance need some energy but if there is no medium then there will be no disturbance hence no energy will be dissipated from the ...
0
votes
1answer
26 views

How does diffraction affect the amplitude of sound?

Let’s say we have a 2D “maze” which represents walls in a space. If we place a sound source somewhere in it, what would be the amplitude at a different point in the maze. Or in a simpler case, given a ...
0
votes
0answers
11 views

How loud would a sonic boom that occurs at 60,000 (and 85,000 and 35,000) ft altitude be to observers at sea level?

I am aware that breaking the sound barrier over the U.S. is currently outlawed, as detailed by this release. So, I was wondering how big of a deal the sonic boom of aircraft would be to those on the ...
0
votes
1answer
25 views

A standing wave with different linear mass densities

I have a question about a standing wave with different linear mass densities throughout the string. Suppose that we had a string of linear mass density $\mu$ joined at $x = L$ to a string with linear ...
-3
votes
5answers
198 views

If I pull a long stick one meter towards me, how long will it take before the other end is displaced one meter?

Imagine that I pull a stick one meter towards me. And say the stick is 100 (m) long. My friend looks at the stick on the other side. How long will it take before my friend sees the stick to be one ...
0
votes
1answer
20 views

What is the microscopic mechanism for the reflection of sound waves?

There are a couple questions similar to this but the answers don't quite answer what I want. In EM, the reflection of light is microscopically described an EM wave accelerating electrons that ...
1
vote
1answer
30 views

High pitched acoustic reverb from semi circle monument

I went on a trip last week and encountered a rather peculiar phenomenon here, when standing in the middle of the circle that's marked by the bricks, and clapping my hands, a very high pitched noise ...
0
votes
1answer
12 views

Resonance in an open pipe with an angled non-squared end

An open pipe (organ pipe) has a narrow, high Q resonance. Is there any research out there for the effect on Q at different angles of end cut? If not I am going to get a carpet tube, a speaker and a ...
2
votes
1answer
54 views

Moving charges emit electromagnetic radiation. So can sound waves in ionized air produce light?

Moving charges emit electromagnetic radiation. Sound wave propagation through air involves the vibration of air molecules. So in principle, can sound waves in ionized air produce light? This post does ...
9
votes
4answers
783 views

Why does a blast wave travel faster than sound?

https://en.wikipedia.org/wiki/Blast_wave#Characteristics_and_properties says: "A blast wave travels faster than the speed of sound and the passage of the shock wave usually lasts only a few ...
1
vote
1answer
47 views

Noise Cancellation - Destructive Interference

We know that active noise cancelling headphones work by playing a signal in your ear which is 180º out of phase with the ambient noise. If we compare the two waves, the peak in one wave is completely ...
0
votes
1answer
19 views

What makes hard magnetic materials more appropriate for use in microphones than soft magnetic materials?

I can't find a reason out there. Surely it'd be a soft magnetic material is best? What makes hard magnetic materials more appropriate for use in microphones than soft magnetic materials?
1
vote
3answers
41 views

Are soundproof foam shapes reflective of audio frequencies?

I came across a previous question regarding how soundproof foam absorbs sound: How does foam "absorb" sound? where the answer explains the properties of the foam itself rather than the shape....
3
votes
1answer
42 views

First harmonic above fundamental in piano recording?

I am currently working on a project, the final aim of which is to see if one can classify which instrument a sound recording is coming from, by looking at the fourier transform of a note and comparing ...
1
vote
1answer
32 views

Would a non-dimensionless reflection coefficient make sense?

I am working with a numerical modelling program allowing to simulate wave propagation in a drill string. The reflected waves are modelled using the reflection coefficient between the drill bit and the ...
1
vote
2answers
37 views

Difference between reverberation and echo? And the factors affecting both of them (unique as well as common)?

Is reverberation caused by echo? Is echo the thing that we hear inside of our rooms? Or is it reverberation? Once such definition states that - Reverberation is the persistence of sound after the ...
0
votes
2answers
27 views

Is the forced oscillation an accurate and/or useful model of how musical instruments work?

I recently learnt of the mathematical model behind simple forced (undamped) oscillations, and typed the equations into Desmos with some parameters here, where something subscript F means something ...
-3
votes
2answers
49 views

Inverse square law of sound [closed]

How can I prove $1/r^2$ based on this equation (Intensity) based on the inverse square law of sound? $I = 8 \cdot 10^{-9} \cdot r^{-1.303}$
1
vote
3answers
72 views

Making a car that uses sound energy [closed]

Can we use sound energy to move a car? What if, instead of an engine, we put something near the tires which make tires move with the help of sound energy? Is this possible?
0
votes
2answers
40 views

How do I find the energy of sound from Audacity?

For a project, I recorded the sounds of a boccee ball impacting with some ping pong balls in a container using Audacity. I also used a sound pressure level meter to record the maximum dB C that was ...
0
votes
1answer
23 views

How sound transmisson differs in closed muffled room from open space?

I wonder, how differs behaviour of sound in two different localization: First, we have open space - only ground and no obstacles. Second, we have a tiny closed room with well-muffled walls. I was ...
0
votes
0answers
28 views

Ukulele string sliding sound

Though it's clear that strings on guitar (or uke) produce different sounds because of difference in vibration frequencies, but why the strings produce different sounds even at the gentle sliding of ...
2
votes
0answers
47 views

How to generate longitudinal acoustic waves in a granite disk. Starting from the center going outwards like dropping a rock in a pond

Diameter of disk: 25cm Thickness: 1cm composition: pink granite Follow-up on my earlier question about injecting 200 watts of power in granite. Among the answers already provided, was the idea of ...
3
votes
2answers
616 views

How to inject the maximum acoustic power into a block of granite?

I know that we can use transducers that are glued to a surface to achieve this. If I want, for example, to have 200 watts of actual acoustic power in the audible range in the granite, is a transducer ...
0
votes
1answer
24 views

How can mean free path affect the propagation of sound in a gas?

I was thinking, since mean free path is a measure of "how long" a particle has to travel to collide with another, that this surely must influence sound propagation somehow. I would say this ...

1
2 3 4 5
46