What is Ultrasound: Definition and 111 Discussions

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.
Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles.

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  1. V

    Therapeutic vs Diagnostic Ultrasound Tissue Temperature

    Hello everyone, I stumble on this forum while searching for reliable explanation of ultrasound thermal energy with regards to temperature increase in superficial human tissue, specifically skin. I have been performing diagnostic ultrasound for almost 30 years, specifically vascular...
  2. C

    I Understanding Ultrasound Attenuation and Reflection in Aluminum Sheets

    Hello. I write this in regards to enquiring whether you can address various questions I have in relation to acoustics and the physics of sound. In particular, I am interested in ultrasound. I have various questions in relation to it. In particular, I am interested in understanding the nature...
  3. Sibilo

    I Can Ultrasound Be Used to Penetrate Through Air and Bone?

    good morning I have a small problem, so can a low frequency 20 - 40 khz ultrasound beam pass through 60 cm of "air" and then 3 cm of bone? Considering the low frequency of ultrasound in this case it is possible
  4. C

    Understanding Ultrasound and Aluminum Plate Interaction: Factors to Consider

    The solution involves understanding the interaction between the ultrasound and the aluminum plate. One factor to consider is the acoustic impedance mismatch which will cause reflection of a proportion of the ultrasound energy. There may be other factors to consider.
  5. C

    I Understanding Ultrasound Blocking: Effects on Energy, Reflection, and Absorption

    Hello. I have a question in relation to blocking ultrasound. Suppose we have a device which emits ultrasound. Lets suppose that is is focused ultrasound, and it emits it towards a target at a displaced location. The question is, if you place an aluminum plate between the target location and the...
  6. P

    B How are fractures in airplane structures detected by ultrasound?

    For applications of ultrasound, detecting fractures using ultrasound is listed in one of my textbooks. According to that, ultrasound cannot travel through air right after it travelled through solid parts of the plane. Therefore if there was a fracture, the sound was supposed to be reflected...
  7. M

    I What is the best way to shield / jam ultrasound?

    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 / jam Ultrasonic Cross-Device Tracking (uxDT). (See "data over audio" and "data over sound") Does anyone have any insight? I am a programmer, and not an...
  8. N

    Acoustic Impendences in this Ultrasound Imaging problem

    Question: Answer: I don't understand about a and c. I just tried to solve b but my answer is still lacking for part b. Can anyone guide me about how to solve these problems and what I did wrong in part b.
  9. N

    Understanding Ultrasound B-mode Imaging: Exploring Lambda and Z Parameters

    a. lambda = 513 X 10^-6 m ZR = 1, 2 cm Z = 1 cm => Z < ZR => LR = D = 0.5 cm Z = 8 cm => Z > ZR => LR = 2 tan(sin^-1 (lambda/D)) x Z = 2 tan(sin^-1 (513 x 10^-6 m/0.005 m)) x 0.08 = 1.65 cm b. t = Z/c...
  10. N

    Can Multiple Reflections Be Eliminated Using A-Mode Imaging in Ultrasound?

    Here is my answer: PART A: Those three didn't surpass 200 us. But, I am still wondering whether I did it right or not since I don t really understand the meaning of `multiple reflections `. I don't know whether I have answered for multiple reflections in my answer above. or should I double the...
  11. R

    Calculating the mechanical index of applied ultrasound

    On the surface, the equation is simply the peak rarefractional pressure divided by the root of the applied frequency: ##MI = \frac{P_{ra}}{\sqrt{f}}## But the pressure is reduced/derated by an attenuation factor/coefficient that is dependent on depth and frequency e.g. ##0.3 \ dB / (cm \cdot...
  12. Moondog

    Fog Droplet Size as a function of Ultrasound Frequency

    I need to know how to predict particle size of a water driplet produced by a given ultrasonic frequency? For example, an ultrasonic fogger will create ~5 micron water driplets at a frequency of 1.75 MHz. I do know that the higher the frequency the smaller the driplet diameter. How is this...
  13. hugo_faurand

    Get electrical signal of a piezoelectric with ultrasound

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  14. loophole

    Water deformation subjected to ultrasound waves

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  15. C

    Understanding Ultrasound Focus and Intensity in Tissue Exposure

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  16. R

    Understanding luminol under ultrasound

    Basically, we use luminol to give a measure of sonochemical activity since it reacts with hydroxyl radicals (formed when water is disassociated with ultrasound). I would like to understand the chemistry of the reaction a little more and would very much appreciate any insights. Here is the...
  17. F

    Can we hear beats between ultrasounds in the audible range?

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  18. vlada113

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  19. T

    How does the size between scatterers affect reflection?

    If a sound wave hits multiple scatterers spaced closer than the wavelength and moving fast but at different velocities how is the reflective beam is affected?
  20. T

    Reflection Coefficent in Ultrasound scan

    Homework Statement Discuss the main advantage and disadvantage brought about by a reflection coefficient being very small, and hence highlight the attributes that an ultrasound scanner must have to fully exploit very small boundary reflection. Homework EquationsThe Attempt at a Solution I am...
  21. D

    Why does piezoelectric need amplifying?

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  22. T

    Pulse repetition frequency ultrasound confusion

    Homework Statement Q:[/B]An ultrasound department seeks your advice regarding scans they perform to visualise and confirm foetal heart beating. They wish to know what imaging frame rate should be set in order to visualise the heart movement reliably but achieve the maximum possible reduction in...
  23. physea

    Can ultrasound pass through metal?

    Hello Can ultrasound pass through metal? How much of it can pass and how thick the metal can be? I couldn't find anything online, I only found some contradicting and unclear information.
  24. K

    Ultrasound waves and the kidney

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  25. P

    How high levels of ultrasound can be created in Air?

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  26. HeartEcho

    Ultrasound Nyquist limit conundrum

    Hi all, I work as a cardiac sonographer. I've been struggling to understand a concept as dictated in ultrasound textbooks and it regards the Nyquist limit. During my work I observed that when I increased my ultrasound transducer frequency (e.g. from 1.7 MHz to 3.0 MHz) when using pulsed wave...
  27. L

    Can Sound Be Captured Like a Photograph?

    Is there any sensor or method that allows a 'photo' to be taken of sound from different places? Similar to an ultrasound that is used in the medical field, but can be used more like a camera. I know about Schlieren Imaging but I'm thinking more like a map of all the sounds at a moment, maybe...
  28. M

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  29. F

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  30. H

    Acoustic Absorption Calculation: Ultrasonic Sound in Water

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  31. W

    Behavior of an ultrasound wave on a particle

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  32. Littlegirloud

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  33. T

    Why Does Mode Conversion Occur When a Longitudinal Wave Hits an Interface at an Oblique Angle?

    when a longitudinal wave beam hits the interface at an oblique angle, we can have both refracted longitudinal and transverse waves, so as with reflected.that's because some of longitudinal waves have converted to transverse waves.but why is that? what is the origin? p/s: sorry for bad English :(
  34. N

    Exploring the Electromagnetic World: A New Scientist's Journey

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  35. L

    Operating a portable ultrasound machine in -30 degrees C

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  36. R

    Why do ultrasound waves not travel through air well?

    I'm at an internship and I saw a container labeled ultrasonic gel, which is used to prevent air from coming between a scanner and the human body. This is necessary because apparently ultrasound doesn't travel through air well. Why is this? (don't say because the density is low, because I will...
  37. NPB777

    Ultrasound Transducers and Simulator

    Presently I am working on Underwater Acoustic Wireless Transmission. I desire to measure water parameters at the bottom of the surface of the water and then pass it to the water surface using Ultrasound. There will be a buoy at the surface which is half submerged and half floating. The floating...
  38. B

    Ultrasound - Doppler angle vs. beam steering angle

    In ultrasound what is the difference between beam steering angle and Doppler angle thanks
  39. B

    Ultrasound spectral broadening

    Hi, I am slightly confused about the causes of spectral broadening and reverse flow in duplex ultrasound so wanted to clarify if I am correct. Here is my understanding. Is it correct? - Spectral broadening typically occurs in areas of parabolic laminar flow, distrurbed flow or turbulent flow...
  40. B

    Why Do Ultrasound Axial Resolution Phantoms Show Stretched Black Dots?

    Hi the image below taken from http://www.gammex.com/ace-files/manuals/411LE_Users_Guide.pdf shows an ultrasound axial resolution phantom. I do not understand why the black dots on the phantom are stretched up-and-down in the ultrasound image. I do understand though why they get wider. Please...
  41. B

    Resolving Phase Ambiguity in Pulsed Doppler Ultrasound

    Hi. I understand the principle behind Pulsed doppler ultrasound. If the echo from a transmit pulse is sampled (gated) during a narrow fixed time period, the echo will correspond to a particular depth. What I do not understand is how we can extract phase information by repeating the process of...
  42. K

    Ultrasound Attenuation: Why Power Ratio?

    Hello, I have a simple physics question. It is about ultrasound attenuation. Why is the attenuation a function of the log of the POWER ratio? i.e. why must it be the ratio of power quantities rather than field quantities? what is the physical basis of this relationship? thank you!
  43. darklord27

    Can an Ultrasonic wave penetrate a LPG cylinder

    Hey guys, First time poster here. Presently I'm doing a project to measure the levels of LPG remaining in an LPG cylinder. I'm currently trying out ultrasonic sensor that primarily works as a distance sensor(HCSR04). As far as I'm aware, the lower the frequency higher the penetration of the...
  44. J

    Acoustic Impedance - Ultrasound Propagation in Tissue

    Hi, I was just wondering why, when the acoustic impedance mismatch is so high between two boundaries at an interface, most of the ultrasound is reflected back. I was just wondering why this happens which I can't seem to find much of an answer to. The only thing I can think of is refraction and...
  45. B

    What Factors Affect Ultrasound Penetration Depth?

    Hi, I want to calculate the penetration depth of some different frequency ultrasound transducers. I know that it depends on the attenuation of the medium but not sure where these types of figures will be hiding. I assume that once the dB lost for the depth is equal to the dB generated, this is...
  46. A

    Designing a variable-frequency ultrasonic wave generator

    Hello everyone! Seeing as this is my first post, I'll give you a basic background of who I am: My name is Andrew Raisbeck; I graduated from university with a Bachelor of Computing (Computer Science) degree a little over a year ago, and I now work full-time for the government of Canada. Since I...
  47. Tony Giaccone

    Measuring density with ultrasonics

    I'm interested in determining the density of a dough. I want to be able to continuously measure the density of the dough as it rises. My thought was to use an ultrasonic wave and measure the time it takes to reflect through the dough I would assume that as the dough ferments and the amount of...
  48. P

    Ultrasound Heat Generation: Equation, Table, and Approximations

    hello! ultrasound can generate heat, right? is there an equation, a table or any other, even approximation, of the heat generated by ultrasound? thanks!
  49. P

    Can High-Intensity Focused Ultrasound Penetrate Metal?

    hello! I want to experiment with High-intensity focused ultrasound I want a kit that produces it so that I can conduct experiments with it do you know where can I buy one? thanks!
  50. R

    Ultrasound absorption by particles in water

    Hi All, I am in need to calculate the ultrasound (20MHz) absorption of particles (polystyrene of size 15 microns) in water. I tried to search in the internet, but couldn't find any simple analytical expressions. Can someone please help me ! Thanks in advance! Regards, Radel...
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