Questions tagged [acoustics]
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63 questions
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How to design an analog filter for an acoustic sensor
It's been a while since I've done this, but I have an acoustic sensor meant to detect low frequency sound waves attached to a 5/32" ID hose that leads out to open air. I seem to recall from my ...
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Is there a dimensionless number for wave guide width and frequency vs turn radius?
It seems like there should be a dimensionless number for wave guide width and frequency vs turn radius, but I have not been able to locate it or understand the proper application of one I am ...
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Designing a siren to vary pitch with port width/pattern. Advice needed
Background: I am trying to design a multi-pitch port siren with one central shaft at 3300 rpm. I've calculated the number of ports needed for each frequency to be n = f(60/rpm). This approach gives me ...
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Can I use a single flat sheet of metal as an ultrasonic horn?
I want to make an ultrasonic cutter for home use projects, something like this or there are many online videos of industrial ultrasonic cutters in e.g. the food industry. A typical design of an ...
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Controlled oscillation of a piano string by electromagnetic, mechanical, or other means
What would be a good way to actively control the loudness of an acoustic piano note over time after the note has already been struck by the hammer, such as by actively changing the amplitude of a ...
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Noise, Vibration & Harshness resources
Would you have a recommendation to learn about NVH. I have a Materials Science and Engineering background. I am looking for learning about NVH in general.
I could find some resources about traditional ...
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Shielding or jamming ultrasound waves using software
I've downloaded SoniControl and it works somewhat well as a jammer, but I am looking for more options.
I'm trying to shield from or jam Ultrasonic Cross-Device Tracking (uxDT). (See "data over ...
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Troubleshooting clipping
I am collecting data for a project, where I am measuring the room impulse response by playing a sine sweep from a speaker (QSC K8 1KW Active Loudspeaker) and measuring it from the other side of the ...
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Simplest way to reduce low frequency noise from windows
Could you please advise the simplest method to reduce low frequency noise from windows?
The problem:
Somewhere outside there is a source of noise with frequency of 166 Hz. I can’t neither find nor ...
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Effect of bracing on a music instrument top - is FEM modal analysis enough to predict this?
I'm currently building a music instrument (string instrument), and I am at the step where one applies certain braces to the soundboard. Since I actually don't know how the bracing will affect the ...
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Confusion over textbook formulae for directional characteristics of sound sources
I'm currently reading Olson's Elements of Acoustical Engineering, in which formulae are given for the directional characteristics of various arrays of sound sources, all of which are stated in terms ...
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Which is the better magnetic arrangement for a voice coil to give a larger amplitude of movement all else being equal?
Given everything else equal (e.g. same overall amount of magnetic material, same strength magnetic material, same coil, same power supplied, etc. etc.) which of these two magnetic configurations of a ...
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What is the mechano-acoustic effect of off-centering the black paste on tabla-drum skins?
Tabla is a musical instrument composed of two drums, the Bayan (left on picture) and the Dayan (right on picture).
A unique feature of the tabla is the tuning [black] paste called the gab, applied to ...
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Help me find a material with low acoustic impedance but high wave velocity
I'm trying to find a material that would have two seemingly opposite qualities. I need something with low acoustic impedance, like a plastic, but also with high wave velocity like a metal.
Here are ...
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Can two microphones placed within centimeter distance together measure a distance of the sound source?
I have placed two microphones placed within 1 or 2 cm distance. They can receive and record sounds around them. I want to detect the distance of the sound source (specially human voice) and the ...
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How loud can an induction hob be?
People that are cooking food with induction will occassionally encounter loud noises from the hob. There can occur a high-pitched whining sound when heating the pots and/or pan. As I searched the ...
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Respirator mask that transmits sound waves
If one had to design a respirator that would have the minimal sound distortion, and allow to communicate normally (one-on-one at least), how would one do it?
I wear powered respirators (PAPR) and ...
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Does an ultrasonic horn increase displacement?
Reading the Ultrasonic Horn Wikipedia article, it states:
An ultrasonic horn is a tapering metal bar commonly used for augmenting the oscillation displacement amplitude provided by an ultrasonic ...
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How to read this UAV Muffler Sound Test Charts?
Just downloaded this UAV Muffler Sound Test Charts (PDF) file from here. e.g. here is an image of the table in the file:
I have several questions on it:
Why is there written a constant number next ...
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Why are there no mufflers for water plumbing?
People who live in multi-unit apartment buildings often need to be careful not to bathe late at night, because their neighbors will be able to hear the sound of the water going through the pipes.
As I ...
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Better way to cancel “hammer beating wall” noise
I live very near a bulding contruction site, so the "hammer beating wall" noise is a constant in my daylife for the next one year and half (when the building construction will be finished).
...
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Why would a "delayed loudspeaker" be so expensive in the 1970s?
Recently, I read about some major musical concert held somewhere in the USA to a record-large audience.
Since there were so many people, not all could see or even hear the music from the main ...
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Will a short brick wall help shield against bass or will it go around?
I have a noisy neighbor (unreasonable and hostile) generating low frequencies that are disturbing. I'm at the point where I realize I need to just build some kind of barrier, and also buy better ...
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How can I calculate the total signal level (noise) of PC fans?
I have a fan on a PC case running at 100% speed making 40dB/A of noise (sound pressure). Then I add a second fan right next to it running at 100% speed making 30dB/A of noise.
What is the combined ...
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How do I calculate hourly LAeq sound pressure level using 1-mint LAeq values?
I have continuous A-weighted sound pressure level (SPL) values at 1 minute time resolution (LAeq,1min). I would like to calculate ...
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Are there materials that are good at transmitting sound but thermally insulating?
I'm wondering if there are materials good at transmitting sound but is thermally insulating? I'm trying to figure out a good material in an engine exhaust application which will pose a barrier to the ...
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Elastic waves in very thin plate
Elastic waves in structural elements are described by
\begin{align}
\rho \frac{\partial^2 u}{\partial t^2} &= (2 \mu + \lambda) \frac{\partial^2 u}{\partial x^2} + \mu \left( \frac{\partial^2 ...
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Estimating the quality factor (decay properties) of an object's vibrational modes?
I am attempting to model the acoustic behaviors of a circular membrane (drum head). I know that software like ANSYS will give me the modes of vibration pretty easy from a simulation.
But what if I ...
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Motor control sounds
I’m curious about the sound made by some types of high powered electric motors and related control devices. Many (but not all) large electrical motor systems make high pitched sounds that correlate to ...
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Is there a technical name for a sound dampening suspended cylinder in loud indoor environments?
Several years ago, I was visiting the Advanced Photon Source at Argonne National Laboratory, and I remember that in one of the working areas there were some large cylinders suspended in the air above ...
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Why is the Cape Elizabeth Fog Signal shaped like this?
On a recent trip to Cape Elizabeth, Maine, I came across this fog signal:
It appears to have an electromagnetic diaphragm in the middle, surrounded by concrete and some very curiously shaped steel ...
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Sound level emissions (IEC 60704-1) spectrum?
I have a very noisy air conditioner that have a 10kHz peak at 75 dB, the rest (fan/compressor/pump) are under the regulation limit.
I would like to understand what is the measurement spectrum. I ...
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Grate that does not cause air rush noise?
I have an air supply grate that is making a roaring noise. It has rectangular slats.
I know the sound is coming from the grate, not the duct, because when I remove the grate, the duct is silent. It ...
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What is tonal masking?
I have checked the definition of tonal masking on Wikipedia and google but I saw the definition of sound masking and auditory masking.
Auditory masking
Sound masking
But I want to know what ...
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Will a 3-wall acoustic barrier work or will sound go around?
I have two heat pumps directly outside my house and they are noisy so I am considering the viability of using a sound barrier to block the sound. The acoustic barrier itself will definitely absorb and ...
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How to reduce resonance from livingroom table
Odd ting, the table surface echo/resonance sound when speaking, especially lower lower frequencies. It helped putting on a cloth, but it did not completely remove resonance. Putting a rug beneath did ...
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Does the stress on exhaust hanger amplify sound transmission into the vehicle chassis?
I have an exhaust that drones with the vehicle. However, outside, it's not a loud exhaust. So my assumption is the vibrations are transmitted into vehicle interior via the points of contact - in this ...
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Acoustics resonance question
I have a complicated cylindrical geometry with a speaker mounted on somewhere middle of the rig. The one end is closed, the other is open. Sweeping the speaker frequency from 0 to 1000 Hz, I tried to ...
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Microspeaker enclosure design for headphones
I want to embark on an acoustic project of designing an enclosure for some 40mm microspeakers, identical to ones found in a typical on-ear headphone solution. Are microspeaker enclosures treated in ...
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How can I calculate headphone driver excursion?
I'm a headphone enthusiast, and once I tried to open up my headphones to see how much they move when I play my music.
However, I was really surprised to see that the sounds that I could "feel" ...
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Modelling acoustic instruments — predicting frequencies, decays, levels, and phases of modes of a circular membrane (drum head)
I have been working on some acoustic synthesis software for modelling several acoustic instruments. I am using the principle of modal synthesis, where every mode of vibration is individually ...
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How do I convert coefficient values from 1/3 octave band to 1/1 octave band?
I have some coefficient values i.e. 74.9, 81.3, and 80.5 at frequency centers ...
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Why aren't these kind of drivers used in loudspeakers?
This is a driver in a headphone. These can produce every sound and beyond that humans can hear. I understand that there are full range speakers that are sometimes used, but they work in a very ...
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Sudden increase in noise levels - subway noise -happend overnight [closed]
This is real life issue I am having currently and I am puzzled as to why it happened. I have lived over the subway lines (two actually each going in the opposite direction, two sets of tracks) for ...
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Optimal size and shape for a steel target?
Problem
I'm building a steel target for long-range rifle shooting. For those unfamiliar, the purpose of the steel is to produce a loud "PING" when the bullet strikes the target. It's very fun.
Since ...
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How well would viscoelastic damping work between isogrid- or honeycomb-faced constraining layers?
I'm considering doing some experiments with 3D-printed surfaces and sound transmission with constrained layer damping. I've also been thinking about using isogrid or honeycomb interior surfaces, ...
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Did the pressure unit "bar" change definitions since the 1930s?
I don't see anything in Wikipedia about it, but (from this question) when I try to reproduce the equations in this 1933 paper, I get values 106 away from the values in the paper. When I reproduce ...
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Are there general-purpose acoustic FFT sensors for plant diagnostics?
For the purpose of detecting a defect or failure in a machine, it is often practical to physically listen to any abnormal noises that a machine might be making, and even use a simple stopwatch to ...
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Which Whistle Type works with the lowest PSI?
I'm working on a project where we are trying to prototype a whistle that works at the lowest possible air pressure and still produce an audible sound.
Any suggestions on whistle type? and any ...
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How much does a wall stop sound?
So I have this problem, every Sunday we have about 200 kids come over to our house in town, and they make a LOT of noise. We also have mildly nice neighbors that do not like noise Sunday afternoon ...
