Acoustics - Science topic

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Generally, the BVD model is used to investigate the electrical characteristics of the emitting piezoelectric ultrasonic transducers. When piezoelectric ultrasonic transducers are used to receive acoustic signals, what equivalent method or equivalent circuit is used to characterize them?

What are acoustic metamaterials?

How to measure green function experimentally in a room in the field of acoustics?

Give an impulse (like a clap or bomb) and measure the pressure. This will give the green function, is it correct?

Hi everyone, I hope you all are fine, I have acoustic data from five different sensors for an underground pipeline. I want to compute the velocity. Can someone give me some suggestions and solutions on how to compute the velocity for all these five sensor data?

Looking forward to your responses!

Thank you all!

i want to calculate the flame transfer function of swirl stabilized non premixed flame. I have a loud speaker at my disposal. Do i need a siren instead of a loudspeaker.

Dear Colleagues,

I am studying ultrasonic response of plants to human interaction. I need help determining the device I can use to detect ultrasonic sound range from 20-120 khz. The Khait et al study of 2023 showed that plants as tomato, tobacco emits ultrasonic popping noises of that range and can produce noise upto +_ 65 dbspl under stresses. I am not an acoustic guy so I need help determining what devices I can use to detect ultrasonic noise of that range?

I am doing a literature review on acoustic properties of layered media and I am struggling to find articles, resources etc to add to the review. Does anyone know of any seminal papers in this field that I should be reviewing?

Dear all, I am trying to model cavitation using Abaqus CAE. The problem is assigning the cavitation pressure. Abaqus CAE doesn't allow to define the pressure. It can be defined in input file using following command (according to abaqus user manual).

*Acoustic Medium, Cavitation Limit

0,

But then again abaqus doesn't read it and gives a warning. Can anyone please suggest me a way to define this limit? The same thing happens for defining initial pressure condition for cavitaiton.

Thanks in advance.

In thermal evaporation process, for the digital thickness monitor to display thickness of films, we need to input, density, acoustic impedance, tooling factor. For standard compositions it is available in literature. What if we made a particular composition, how can we find it?

What are the statistical methods and tools available in Praat for analyzing and comparing acoustic phonetic data across different groups or languages?

I understand the physical mechanism of either negative mass or negative bulk modulus of acoustic metamaterial, but paper seems to use analogous electromagnetic model or just equations to demonstrate that "negative refraction needs both negative mass and negative modulus".

However, I am confused about the physical mechanism behind it. Is there any paper or book illustrating this? Thank you.

I would like to know about tools that can support acoustic PHY layer and various ad hoc routing protocols for multi hop communication in underwater networks. What are their important features and functionalities?

For the acoustic design of an enclosure, is it enough if the natural frequencies of the enclosure do not match the frequency of the sound generated? Such an approach to vibration would be fine. Is it okay for the acoustic design? The enclosure is a simple box and the sound is generated at a single frequency. Thanks in advance for your answer.

An example of achieving negative effective mass density is membrane-type acoustic metamaterials, which exhibit a negative mass density below the cutoff frequency.

We plot it using the formula given. (theoretically)

But now I am facing a problem regarding the negative effective bulk modulus.

Is the Helmholtz resonator capable of showing a negative bulk modulus?

If so, then whether the Helmholtz resonator is an acoustic metamaterial or not

Assume an underwater acoustic communication scenario. If there is a transmitter hydrophone at 10m depth and if it transmits an acoustic signal to an AUV located deep into the ocean (assume the AUV is located at 3000m depth), then how do we calculate the range that this acoustic signal can reach to the AUV into the sea? What is the formula to be used to estimate the range between transmitter and receiver?

Let us consider that we are using an underwater acoustic transducer Model 630 in an underwater AUV application. Usually in the data sheets, the manufacturer provides the details of operating frequency, input poser, operational depth, typical receive response, and transmit response. Suppose I want to calculate the typical receive and transmit responses, then what formula is to be used?

Do you have any idea about the measurement of the roads surface quality with acoustic methods?

Can we understand by acoustic methods whether the roads surface is oily, snowy, dirty etc.?

Which acoustic method can we use?, is the method already developed?

We have observed in literature regarding the optical mode and acoustic mode in FMR spectra.

How to identify which one is acoustic and which one is optical?

Kindly clarify.

Assume an underwater scenario. There is a ship on the sea surface and an AUV or ROV in the ocean at a 3km distance. If the transmitter transmits an acoustic signal, how do we calculate the range covered by that signal to the receiver? What is the formula used to calculate the range and received signal strength in dB?

Dear ResearchGate members,

On one hand, there is a theory giving the reflection/transmission coefficients when acoustic planes waves propagating in a medium (rho0, c0) reach a finite thickness object (rho1, c1) with normal incidence. Such theory basically gives the thicknesses (n*lambda1/2) at which the object is theoretically acoustically transparent - of course, the width of the reduced reflection depends on the impedance mismatch between the 2 media – and the thicknesses ([2n-1]*lambda1/4) at which the object is fully reflective.

On the other hand, there is also theory giving the variation of the reflection coefficient depending on the incident angle of acoustic plane waves at the interface between two semi-infinite media (rho0, c0; rho1, c1). Over a critical angle (depending on the impedance mismatch between the two media), the reflection is theoretically total.

Now, here is my question: What is the behavior of the acoustic waves when the two phenomena are considered at the same time? If the plane waves reach a surface with an incident angle, and the reflective medium is finite in thickness (acoustic mirror)?

By experience and through simulations, it appears that over the critical angle, the reflection is not total, even with a mirror thickness for which the reflection is theoretically total.

Thanks a lot in advance.

I’m currently in the process of selecting a research topic for my doctoral studies. I have a keen interest in the field of acoustic metamaterials. I would really appreciate if you are helping me to provide your expertise and suggestion to select the topics in the field of acoustic metamaterials

Dear expert,

How to do Distributed Acoustic Sensing for MASW purpose, if it can be done can the geophone planted on surface in vertical, for subsurface imaging ?

Really appreciate if it can be done?

In general, it is difficult to effectively divide the difference between tuff and dacite by natural gamma curve and acoustic time difference curve in some work areas, and both show low GR value and low DT value.

It is well-known from the literature that there exist diverse acoustic waves in compact astrophysical objects, such as white dwarfs, neutron stars, etc. Can anyone please give us a concise glimpse of the state-of-the-art astronomical observations of such existent acoustic wave spectra?

As the eigen room modes of a room are complex. So How to remove the complex eigen modes? Is there a way to remove the acoustic damping by air in SOLVER SETTING?

#COMSOL #ROOM ACOUSTIC

It seems to me that everyone just refers to J. W. Goodman's book "Speckle phenomena in optics: Theory and Applications". I agree this is a good book, however in my opinion there are some differences in ultrasound.

I would like to find answers to the questions:

- how realistic is it to assume that the ultrasound signal has a single spectral component (monochromatic light assumption in Goodman)? Is this assumption required?

- what is the effect of ultrasound transducer and the transformation from pressure to RF signal?

Thank you for your answers.

Hi All,

I wonder how I can use infinite elements in CEL (Coupled Eulerian-Lagrangian) models in Abaqus to absorb waves at the boundaries of the soil domain. The only available element type in CEL is EC3D8R (Eulerian hexahedral 3D elements with Reduced integration) and acoustic or infinite elements are not available. As an alternative, I created a non-Eulerian (deformable) part, tied it to the Eulerian part, and intended to assign infinite elements to this (non-Eulerian) part in the input file. However, I encountered an error that "Eulerian elements can not be tied to non-Eulerian elements".

Could you please, provide some advice?

Thank you very much.

Pourya

discussing about sand monitoring on deep water subsea wells, is there any threshold that we can refer to when we read ASD (Acoustic Sand Detector)?

when we can saya that the value reading is representing sand or representing the fluid flow?

thanks and please correct me if there is anything wrong with my appellation

Specific: frequency or time domain? acoustic or elastic media? with attenuation or without? using CPUs or GPUs? ... ...

The results of our research determined for the first time that for the entire frequency range of acoustic waves, the range of their propagation, measured not in units of measurement of distance, but in cycles, is a constant: the same number of cycles corresponds to the same absorption of acoustic energy. Due to the difference in the lengths of acoustic waves, the range of sound propagation is determined by the wavelength, which for the conditions of the practical absence of sound dispersion in water, has a statistical relationship with the wave frequency. Due to this, the researchers got the wrong impression about the dependence of the sound propagation distance on the frequency. But the presence of correlation in this case is not related to the presence of a cause-and-effect relationship between the frequency of acoustic waves and their propagation distance. Thus, for the first time, the basis for a complete rethinking of the theory of the process of absorbing the energy of acoustic waves in water is presented.

It should be noted that there are signs that the obtained regularity can be extended to transverse waves in water. This is evidenced by the fact that, unlike shorter wind waves, long ocean surface (transverse) waves of "surge" spread over a distance of more than 1000 km. Tsunami waves, which have a length greater than the length of "Zibu" waves, spread over a distance of tens of thousands of kilometers. Seismic waves that propagate in the solid shell of the Earth, at lengths close to the length of tsunami waves, also propagate for tens of thousands of kilometers. In the future, different types of waves propagating in different environments can be considered, which does not exclude the possibility of confirming the general (universal) physically justified and understandable regularity of wave attenuation put forward by us.

Recently, I want to study the acoustoelastic effect of Lamb wave in composites, and use this property to measure the stress of carbon fiber reinforced composite T300/QY8911. The third order elastic modulus parameters of materials are required for the acoustic elastodynamics modeling. However, I only found the relevant parameters of T300/5208 in the paper, and did not find any relevant parameters of T300/QY8911. I wonder if anyone knows these parameters and would like to share them, I would appreciate it!

Hi all,

Is there any tutorial on acoustic Fresnel lens simulation in COMSOL? I want to start the simulation of the fresnel lens in COMSOL.

I am working on a project in which I need to analyse acoustic data taken from voice recordings of a person in different rooms. I wanted to know if there are any parameters that are independent of the environment and therefore do not change by changing the room setting (e.g. standard deviation of acoustic pitches). Also, I would like some reference if you have.

many thanks!

I wish to perform acoustic phonetic analysis of Oral and Nasal vowel phones in a language. I am aware of F1-F2 plot helps in plotting oral vowel phones, but having the confusion of same can be used for nasal vowels. Please suggest me some good reading materials related to acoustic phonetic study of nasal vowels.

Acoustic inside the mosque is affected by different creteria such as form, space design , material, insulations, AC,...

What do you think?

Dear Researchers,

I am looking into deriving the particle displacement for pressure acoustics in the frequency domain or transient domain. If I solve a acoustics problem in comsol I get the pressurefield and derived variables like acoustics velocity and acoustic acceleration. How could I derive acoustic displacment from these variables. Displacement is the Timeintegral of velocity and in simple cases It is easy to derive the displacement, but in more complex cases I am lost onto how to solve for particle displacement.

Can anyone pont me in the right direction?

Conceptually, as well as source of wave propagation and wave equation

Dear RG community,

I'm starting a photoacoustic project, and I need to acquire some ultrasonic receivers.

Acoustics is not my expertise, so I'm asking here for help! :D

Where to buy, what is the price range, and what to pay attention to?

I am looking for the maximum bit rate for underwater acoustic communication and communication distance. Please suggest to me some related papers.

Microphone array is heavily used in acoustical techniques such as detection, DOA, target tracking and so on. I'm wondering if there is a user-friendly code or toolbox that can be used for demos in the classroom for an acoustic course for master/bachelor students.

We've recently been investigating alternatives to glass/plastic particles for Acoustic Doppler Velocimeter seeding material that can be disposed of without environmental concerns and are less costly. One alternative we have tried is kaolin clay, which has seemed to be quite effective in initial tests. I was wondering whether anyone else has experience using this or if there are any other alternatives that we should consider?

explain to me the parameters that can influence the acoustic and elastic properties of materials

I have studied the literature and found that combining a Helmholtz resonator and membrane results in a negative effective mass density and a negative effective bulk modulus. Typically, in double negative acoustic metamaterials, we find two resonant frequencies, one due to the Helmholtz resonator and one due to the membrane. Is there any possibility that we get only one resonant frequency in double negative acoustic metamaterials?

I want to model a vibrating solid (ultrasonic horn) in liquid filled structure and observe the acoustic pressure field in the liquid.

I used solid mechanics (frequency domain) and laminar flow (stationary), but it didn't work.

I think it is because solid mechanics is frequency domain but fluid mechanics is not.

If I don't use fluid mechanics, I can't select the properties of the liquid.

please help me.

Can I get some comments or examples?

I'm preparing a model related to the phenomenon of leak detection by acoustics in gas pipeline . The case is transient encountering injecting of an acoustic wave signals in the domain . After invistigation of results , i found that the results are mixed with reflected wave coming from the end of the pipe.So i need to eliminate the reflected waves by means of end condition that can absorbes all the reflected waves . NOTE (I already used perfect matched layer for frequancy steady state studies but it doesn't work with transient studies ) .

thanks for your supports .

Can anyone recommend a usable resource/tool for species detection from acoustic data please? A middle ground between a phone app and something like Arbimon would be about the level. Briefly, a phone app lacks flexibility in data collection, i.e. it cant be left out all night or left running for long periods. However, Arbimon is not that useful to anyone below ecologist level, as it only tells the user what species is present if the user completes their own validation, i.e. the user has to identify all species themselves. I'm looking for something that can analyse data from an AudioMoth, uploaded by citizen scientist participants, and actually identify species.

hello everyone,

what is the criteria to decide the position of an acoustic black hole (ABH)?

I don not address beams which ABH is usually considered as a tapered edge. I am addressing plate and shell structures with a wide design space.

I think the criteria could be maximum normal nodal speed which is directly relevant to radiated noise.

Let me know you ideas, engineers :)

Could anybody tell me the name for acoustic counterpart of RFID? Any references on that? Thank you!

Dear R^G specialists, I am wondering if is there a phase transition to a localized transversal phonon sort of coherent state? We know that there is one for the diffuse photon field when light scattering becomes strong enough (frozen light limit [1,2]).

This question arises only for transverse waves [3,4].

Following [1] Frozen light, Sajeev J. Nature volume 390, pp. 661–662, 1997:

Are there strong interference effects, due to the wave-like nature of transverse phonons, which severely obstruct their diffusion?

We already know that electrons & photons can be localized, please see the following articles & references therein:

[1]https://www.nature.com/articles/37731

[2] https://www.nature.com/articles/nphys2278

[3] https://www.nature.com/articles/s41524-020-0295-8

[4] https://www.seas.upenn.edu/~nanolab/files/publications_pdf/confpapers/2007_SHTC.pdf

I am required to make a report on the relation between the mechanical waves' domain and the Electromagnetic waves' domain.

I understand both are fundamentally independent of one another so I am confused of the request and willing to learn if there exists a direct relation (as in physics of the two waves) between the two types.

Sensor is designed for maximal temperature of 130°C, pipe surface depending on application reaches 200-450°C. The isolation pad must have satisfactory acoustic conductivity of ultrasonic signal in frequency range between 0,2 to 5 MHz. The isolating pad should be several mm thin. Maybe some kind of cooling layers in required dimensions could be used. Contact surface of the sensors is in dimesions up to 40x80 mm.

I have, as the outcome of data collection, three groups of music that have been used for different purposes. I have collected many different types of information about the individual pieces of music (pitch range, speed, acoustic properties, perceptual ratings of emotional content etc.) and I wish to determine what combination of these variables best explains the original grouping of the music. What statistical analysis method should I use? Thanks in advance.

I am at loss how to start my acoustic analysis. In fact, I downloaded many softwares and none of them could serve the purpose.

Hi,

I'm looking for a small (less than 0.5m of max length) underwater sound source to do some experimental measurements, any recommendations?

I'm looking for something robust and reliable but with prices ranging from lowcost to lab equipment.

All the best

which is efficient model to generate band gaps for acoustic meta materials

Hello,

I just want to discuss a few things about the non-reflecting boundary condition (NRBC) function in LS-DYNA. In fact, I am studying a fluid-structure interaction problem using LS-DYNA Finite element explicit code. My main interest is to study the propagation of shock wave as well as its interaction with the structure. So, I modelled the fluid part using solid acoustic elements (along with *MAT_ACOUSTIC) in LS-DYNA. Then, I applied the pressure to the fluid elements. But, the problem is that I cannot introduce both loading and boundary conditions (NRBC) on the same segment at the same time. It happened that the non-reflecting boundary condition that I introduced does not seem to be working.

So, I would like to know if there is any way to activate the non-reflecting boundary at a later time step different from the load application time (preferably at the end of my loading phase).

Thank you very much.

Regards

Ye Pyae Sone Oo

As we know Maa et all have pioneered the theoretical calculations on Acoustics Impedance and Absorption by introducing the concept of micro-perforations. While preparing some theoretical predictions over the experimentally generated data many of the calculations in literature contradicts and seem a little confusing with imaginary terms and differential equations.

Are there any suggestions on some simplified calculations and methods that can be applied for theoretical modeling in MPP acoustics for the determination of Sound absorption Coeeficeint?

Experimental results of the Sound absorption coefficient of material have mostly been found to be in good terms with the Theoretical models. But the calculations look confusing. With imaginary terms and differential equations.

Are there any simplified calculations and methods for theoretical modeling in acoustics?

I am using 2 ultrasonic assembly for cleaning purpose and I want to increase cavitation intensity.

(1) a ceramic transducer with a diameter of 30 mm and a horn with a end diameter of 8 mm.

(2) a ceramic transducer with a diameter of 40 mm and a horn with a end diameter of 8 mm.

Since the input power of (2) is higher than that of (1), I expected that the sound pressure of (2) is higher than that of (1), but it was not.

I think it is because the acoustic impedance of (2) is much lower than that of (1) (even though the power is high, sound pressure can be lower since Z=p/v is lower).

1. Am I misunderstanding something??

2. If not, how to increase the acoustic impedance of the ultrasonic assembly??

3. How can I estimate the acoustic impedance of the ultrasonic assembly??

4. What is the best?? the acoustic impedance of the ultrasonic assembly should be equal to the acoustic impedance of the media (water in my case) or as high as possible?

I think if the amplitude is large then the acoustic pressure also high.

I have tried to increase the acoustic pressure and use the ultrasonic booster which is known to increase amplitude.

But it did not work. The acoustic pressre measured by hydrophone was almost same as the acoustic pressure of the transducer without booster.

I am wondering

1. What is the relationship between the acoustic pressure and the amplitude.

2. What is the ultrasonic booster. Does it can increase the acoustic pressure??

If yes, please indicate an example.

i am doing thermal evaporation of pentacene and dntt polymer. just want to know the acoustic impeadence

I am asking about how to find a formula for acoustic impedance for a porous wall with a variable thickness. The impedance is defined as a function of acoustic resistance (R) and acoustic reactance (X). The formula for the impedance is attached. In the case of having a wall of the same porous material, but the thickness is changing.

How the formula should be modified?

where,

R : acoustic resistance

X: acoustic reactance

X1: Mass coefficient

X2:cavity coefficient

w:frequency

Greetings! Looking for an advice on possible technical literature about specific subject: Influence of an acoustic waves on electronics and it's failure mechanics. If anyone is familiar with respectable source of information, please let me know. Thanks in advance!

I have two IDTs (interdigitated transducers) orthogonal to each other o a piezoelectric substrate. I want to know what happens when an RF signal is applied to both the IDTs at the same time. how to find out the orthogonal interference of two acoustic waves?

1) I would like to know how to choose the acoustic sum rule for phonon calculation in Quantum Espresso for polar materials and also for any materials in general.

2) Based on what criteria we have to choose the acoustic sum rule for a particular material under study.

3) I would also like to know the detailed theoretical explanation behind this.

The aim is to characterize a DAS instrument connected to a fiber optic cable.

what are the properties that I should look into ? white noise ? Dynamic range? SNR ?

I did some choc tests and I'm thinking on how should I calculate the SNR. Should I calculate a SNR for different frequency band ?

Thank you in advance,

I have to understand the use of green's function in acoustics . What does it signify ?

I want to optimize the placement of the sensors on a 3d terrain which is created in the arcmap.

I want to find the optimum no of sensors to be used on the terrain,

can you help me in the algorithm part.

Acoustic field modelling, structure fluid coupled responses

Hello,

I am trying to find acoustic round-trip latency of Android smartphones. I have using the technique of where I play a beep and listen to it through the phone and then perform convolution and get time index where we get the peak value.

Here the issue is that when we play our beep, the AEC and NS of Android smartphones cancel and attenuate the beep and it cant be seen in recorded data.

Most of the applications that measure acoustic latency such as the OboeTester app etc. use VOICE_RECOGNITION (https://developer.android.com/reference/android/media/MediaRecorder.AudioSource#VOICE_RECOGNITION) mode. In this mode, no DSP is performed and we get raw data. But this excludes the latency of DSP algorithms performed by the built-in components.

I want to find the round trip latency using VOICE_COMMUNICATION mode. In this mode, all components of AEC, AGC, and NS are activated. But this cancels our beep and we can't get accurate results.

Is there any want to find latency while AEC and NS are working. Looking forward for the solution.

Regards,

Khubaib

We know that by using a microphone array we gain extra SNR. In the meantime, vector sensors are also with that advantage, and moreover, able to achieve that with a single sensor without the necessity of using an array. However, the reality is nowadays most acoustic products are using a microphone array instead of a vector sensor. Why is that?