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.

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Ultrasound acoustic coupling gel loosing its form

I am working on an experiment that uses an ultrasound probe and an acoustic coupling gel. The gel is stored in a standard storage container as this: I am applying the gel on the probe's surface: ...
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How does transition from supersonic to subsonic flow occur?

I was working with orifices that were restricting flow and had to do a few calculation to verify some measurments (and to see if stuff was within tolerances). So I stumbled upon the calculations our ...
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Why don’t different notes create acoustic beats?

Why is it when two different notes are played in unison an acoustic beat is not heard, but when they same note slightly out of tune is played beats are heard?
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Reflection of sound wave passing through gas to solid and through solid to gas

Why following are true in both cases?. 1- Ultrasound passing through a metal block(solid medium) will not pass through a cavity (air medium) inside the block. I got some explanation as speed of sound ...
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2 sounds reaching ear within 0.1 seconds and after 0.1secons

Some books suggest that if two sounds reaches our ear within 0.1 seconds then ear or brain perceive them as one sound and to hear an echo the time difference must be of at least 0.1 seconds. What does ...
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Measured frequency of the sound produced when blowing in a bottle is half of calculated

Preparing one lecture about resonance in cylindrical tubes with one closed end, I decided to make some experiments to compare calculated frequencies and measured ones. We can find anwhere (click here, ...
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Speed of sound in air experiment without measuring internal diameter

Experiment details: https://prnt.sc/GtiGLOq4Ocsk The equation $c = \lambda \cdot f$ is for the speed of sound in a medium. When doing an experiment by adjusting the length of a column of air, the ...
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What defines the speed of waves? [closed]

Why the speed of sound or speed of electromagnetic/gravitational waves have values which they have? What defines it? Why do it not two times slower or two times faster, for i.e.?
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Is timbre a physical noumenon or a perceptual phenomenon? [closed]

I have a question relating the "timbre" of a sound, namely what is exactly and exhaustively defined by this word? Most definitions that I come across seem somewhat loose as "the color ...
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Why is it harder to hear someone underwater than on air? [closed]

Because water is denser than air, sound waves travel faster and with more energy in water than air. However, we are worse at hearing in water than in air. Why is this? To clarify, I was comparing ...
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Parameters which affect the transmission strength of a signal (vibrations) in a solid?

I'm working on a pair of devices - a signal injector and a matched detector for vibrations in solids. My background is not in acoustics, so I'm looking for pointers on what are the parameters that ...
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How do mass and momentum travel in wave? [closed]

In my book what i read was ; In transverse wave - Only Energy is transferred (not Momentum and mass) while in longitudinal wave - Energy , mass and Momentum are transferred. [ Note : The above ...
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What actually is interval of two notes? [closed]

In my book, it is written that if the two notes have frequency $p$ and $q$ then the interval between them is $p/q$. But while solving a question, I found the answer which is like $q/p$. After surfing ...
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How loud is the Perseus cluster?

The gas near the center of the Perseus cluster exhibits quasiperiodic pressure oscillations that can be interpreted as sound. I found a paper that says that these pressure waves have a wavelength of ...
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Why does a sound of two sources of same-amplitude come out louder than one-source sound with the same amplitude?

Sorry if the question is stupid. The last time I touched physics was in school and I have never come back to it since. But this question popped up just recently in my life and I realized I don't know ...
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What do I hear when I hear a diesel car running? [closed]

Diesel engines in cars are notoriously loud. When I hear one, it feels like I can hear it rotating, it sounds a bit like the way I would pronounce a “rolling r”. Today it struck me: the RRRRRRRRRRRR I’...
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Why do some pressure fluctuations in fluids move at the speed of sound or faster and others do not?

If we consider classical pressure waves, whose amplitude is small compared to the ambient pressure, they propagate ~ at the speed of sound. If strong pressure peaks occur, the shock waves can also ...
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What is the best shape of these 4 to make a parabolic microphone? [closed]

I'm building a parabolic Microphone I have found 4 inexpensive reflectors (actually repurposed squirrel baffles). Which in you opinion would be the best? They are all slightly different shape.
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Acoustic absorption coefficient of Metals

Which non toxic Metals have the lowest Acoustic absorption coefficient?
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Sound conduction in a stethoscope

i am trying to build a stethoscope and since i have no idea about physics and acoustics i wanted to ask some questions, hoping Somebody can help me. I mainly have some questions regarding the tubing ...
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Dependence of speed of sound [duplicate]

Why does speed of sound only depend upon elasticity of medium and not on frequency of vibrating particles of the medium?
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Nodes in the air column are not always acting as nodes?

There are many representations of a standing wave column in lets say open-open instrument like flute. In this case one node centrally, and 2 anti-nodes at the openings. However, nowhere do they ...
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What property of styrofoam creates that awful squeaking sound when it is rubbed?

See title. I will accept closure as duplicate of this question, but intuitively (as far as one can trust intuition in these matters) it seems like something different is occurring in the plastic/...
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Speed of sound in a gas (for adiabatic perturbations in cosmology)

In the book "Introduction to Cosmology" by Barbara Ryden, equation 4.57 gives the sound speed for adiabatic perturbations in a gas with pressure P and energy density $\epsilon$. The equation ...
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Ultrasonic pulse-velocity measurement observation

When measuring 80cm thick concrete slab with pulse velocity technique (~22kHz transducers), we get about 210us transmission time - 3,800 m/s, which is in good agreement with expected P-wave velocity. ...
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Could a pure-transverse acoustical-wave propagate?

This is the Wikipedia definition of acoustic waves: Acoustic waves are a type of energy propagation through a medium by means of adiabatic compression and decompression Rayleigh surface waves (solid-...
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Why is the local component of sound particle-velocity not associated with a local component of pressure?

A sound wave can be described by the pressure field or the sound air particle velocity (acoustic flow). Both are intrinsic to any sounds, i.e. there is no sound wave if no pressure or no particle ...
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Speed of sound in thin rods vs infinite solids

This is a followup to this answer, which states that there are two different sound velocities in a solid depending on the geometry: For 3-dimensional, infinite solids, in which the boundaries are ...
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Why does sound follow the laws of reflection, I read in Feynman lectures that Q mech is the real reason for Fermat's principle but why sound follows?

You can also check out science asylum video on how mirrors work, he explains similar thing as written in Feynman lectures. But I do not understand why sound should follow the same thing
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When the levels of a medium that carry soundwaves are low, does that make the carried sound audibly quieter or not travel as far?

When there isn't a medium to carry soundwaves (like air) there isn't an audible sound heard by the human ear. My question is: if air is present, but at the lowest level possible to carry a soundwave, ...
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Acoustic resonance inside an enclosed sphere

I apologize if this question is too basic. Assume an acoustic source suspended at the center of a hollow spherical shell. (The reason why the central acoustic source is suspended inside the sphere can ...
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If there is a way to create an antigravitational chamber how would it be created? [closed]

First off, physics is not my major rather it is a hobby that I have gained basic knowledge of over the years. Private research has led me to a hypothetical question: If an electromagnetic device was ...
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Is it possible to calculate how a wind instrument will sound just based on its geometry?

It seems like it could be done like a cellular automaton, if I enclosed a very-fine 3-d grid within a surface and use cube-cell rules to define how the particles will bounce and propagate the wave ...
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Piano on the moon

Imagine a piano on the moon. You strike a chord. Since there is no atmosphere, there is no medium for the sound to travel. so where does the sound energy go? Does it just dissipate as another form of ...
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What is the function of air cavity in drums?

I'm trying to understand the function of the air cavity inside drums. I've read that 'The air cavity inside the drum will have a set of resonance frequencies determined by its shape and size. This ...
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Does ultrasonic sound travel the same way "normal sound", which human can hear, does?

Please excuse my terminologies if they are not accurate as I am not an expert in physics. For the sake of my question, if I may, I would simplistically call "ultrasonic sound" the sound that ...
6 votes
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Why is this a right angle in the mach cone?

This and similar depictions are used when deriving the equation for the Mach cone angle $\theta$. It is usually stated that using algebra we can conclude that $$\sin\theta=\frac{ct}{vt},$$ and thus $$...
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Why do we hear frequencies in the basis of sine waves?

When we talk about hearing frequencies and overtones, we almost always mean in the basis of sine waves, according to a standard Fourier decomposition. Couldn't we also decompose a signal into a ...
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Can we quantify the pitch of a sound that is a mixture of many frequencies?

How is the pitch of a sound defined quantitatively when it is a mixture of many frequencies? For example, the sound emitted by a plucked guitar string, or say, the pitch of somebody's (normal) voice. ...
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Can wind change the direction of sound propagation?

CONTEXT: I asked this question and the first answer stated that wind cannot change the flux of sound waves through an area. Why is this? I understand that sound waves are basically a bunch of medium ...
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Is upper-atmospheric lightning loud?

The upper layer of the atmosphere has much less density, and pressure. Do phenomena like blue jets, or gnomes even make a sound?
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Wind and sound waves [closed]

The official answer is C. Why not A? If I add a horizontal component of velocity towards left, why would the path become curved?
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Confusion with Doppler effect problem

A detector recedes from a stationary source of sound with a speed that increases continuously and without any limit. Describe qualitatively, the frequency of sound detected by the detector. Assume ...
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How to distinguish between zeroth, second and higher order sounds?

As I understand it, be it liquid helium or phonons in a solid, one can define the second sound, zeroth sound and higher order sounds as quantum mechanical effects where heat propagates as a wave. ...
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Why does the speed of sound in water not increase proportionately with temperature? [duplicate]

I was just wondering, as per this graph (https://www.engineeringtoolbox.com/sound-speed-water-d_598.html) why the speed of sound in water does not increase proportionately with temperature. Instead ...
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Can the dynamic between high speed sound media and slow one preduce shock wave?

Suppose there is two long media that in one of them the speed of sound is high and in one of them is slow. Would the vibration in the one with the higher speed of sound would cause shock wave in the ...
4 votes
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Sound waves adding up [duplicate]

If there is a swarm of bees, why is it louder than a single bee? This question may sound stupid but ... if they are all buzzing at the same frequency with the same loudness and the phases of the sound ...
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Maximum oscilations of air molecules

I read that the maximum oscilation of air molecules in a sound wave occurs at its nodes. Is this correct? If so, why?
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How to solve the Helmholtz equation in damped oscillator BCs?

Given the surface of the vibrating object $\partial \Omega$, I am trying to simulate its outer sound pressure field $p(x)$ by the equivalent source method.[1] For ...
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Why the amplitude of monopole solution in Helmholtz equation is complex?

1. Background Given an surface of vibrating object $\partial \Omega$, I am trying to simulate the outer acoustic field. I use the equivalent source method[1], which ...
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