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Thread: What materials if any are difficult for ultrasound to travel through!?

  1. #1 What materials if any are difficult for ultrasound to travel through!? 
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    What materials if any are difficult for ultrasound to travel through!?


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    What is this obsession with blocking ultrasound?


    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
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    Quote Originally Posted by AlexG View Post
    What is this obsession with blocking ultrasound?
    The fact that I haven't received any answers to this question directly yet.
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    I didn't realize you were worried about the Federal Aliens making you go bald.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
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    ~ I can answer your question.. As I have worked with Ultrasound as one of the many tools in our box used for scrutiny of the rock structures of sea bed strata s.. While looking for petroleum bearing structures.. and right through the spectrum to evaluating fault motion history and Volcanic uplifts and vents on the oceans floor.. Mapping of the seabed is a science of considerable complexity that involves many facets of science. You want to know what would screen you from such probing ? A vacuum. Like a double glassed window.
    It will only shield ultra sound.. sound. Other methods of probing the Earths depths and crust are not able to be shielded..
    ' Is this the second attempt at this question..? '
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    Maybe you need to look at the work done on ultrasound imagery for medical use.
    Ultrasound can be attenuated through absorbtion or even reflected if the difference in the material being probed are high enough.

    I can't give you specific materials that will block ultrasound for several reasons. First is I would need to know if the blocking was to be by impedence or reflection.
    Impedence would mean you wanted to make the surface vanish as far as the probe was concerned, reflection would mean you simply want to hide something behind a clearly visible barrier.

    Next I would need to know the specfic frequency you wanted to block and the sound pressure being used.

    Next I would need a set of material property tables listing the accoustic impedence of the materials.
    Finally I would need to be an actual expert in the field so I could make a sensible recommendation.
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    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    You keep asking this question even though you've received many answers. Part of the problem is that your question is vague -- you have not specified any boundary conditions. How is the ultrasound getting to the material? Through air? Some other medium? What is the frequency? Is it a single tone, or does the spectrum occupy a large bandwidth? How much attenuation do you need? And does the material have to be optically transparent? Is weight a factor? Etc. The list goes on and on.

    In the absence of specifics from you, all we can do is point out the following: There are two general mechanisms by which you might block acoustic (or electromagnetic) energy: Absorption and reflection. The former essentially converts the ultrasound energy into heat, while the latter bounces it back to the source or otherwise scatters it. You can, of course, combine these two mechanisms (stealth technology exploits both).

    If the ultrasound is propagating through the air, reflection merely requires a material whose acoustic impedance is very different from that of air. Astromark's vacuum is one example of exploiting that principle. Another is related to the medical ultrasound example that dan hunter mentioned. The acoustic impedance mismatch between air and meat is rather large at the multi-MHz frequencies used in ultrasound imaging, which is why intimate contact using a gel is required.

    You need to be much, much more specific in order to receive any more specific answers. You seem to think that there's a material that automagically solves your problem, but there isn't.
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    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    Bone. Look at any fetal ultrasound. (One reason ultrasound isn't used to evaluate anything in your head.)
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    Bone. Look at any fetal ultrasound. (One reason ultrasound isn't used to evaluate anything in your head.)
    Hmmm...I think that bone itself conducts ultrasound rather well. The reason that ultrasound imaging doesn't work well with bone is likely due to the huge impedance mismatch between meat and bone. Most of the energy gets reflected from that interface, largely hiding from view what is within the bone.
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    Quote Originally Posted by tk421 View Post
    Hmmm...I think that bone itself conducts ultrasound rather well. The reason that ultrasound imaging doesn't work well with bone is likely due to the huge impedance mismatch between meat and bone. Most of the energy gets reflected from that interface, largely hiding from view what is within the bone.
    True, but the OP seems to be looking at ways of making a "helmet" that will keep government mind control ultrasound out of his head. Given that, the reflectivity of the bone/tissue interface will accomplish his goal admirably.
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by tk421 View Post
    Hmmm...I think that bone itself conducts ultrasound rather well. The reason that ultrasound imaging doesn't work well with bone is likely due to the huge impedance mismatch between meat and bone. Most of the energy gets reflected from that interface, largely hiding from view what is within the bone.
    True, but the OP seems to be looking at ways of making a "helmet" that will keep government mind control ultrasound out of his head. Given that, the reflectivity of the bone/tissue interface will accomplish his goal admirably.

    In that case he could wear a meat helmet. The air gap in between it and his head would provide a nice mismatch, and he would have a handy source of nutrition if on the run.
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    Quote Originally Posted by tk421 View Post
    Quote Originally Posted by billvon View Post
    Quote Originally Posted by tk421 View Post
    Hmmm...I think that bone itself conducts ultrasound rather well. The reason that ultrasound imaging doesn't work well with bone is likely due to the huge impedance mismatch between meat and bone. Most of the energy gets reflected from that interface, largely hiding from view what is within the bone.
    True, but the OP seems to be looking at ways of making a "helmet" that will keep government mind control ultrasound out of his head. Given that, the reflectivity of the bone/tissue interface will accomplish his goal admirably.

    In that case he could wear a meat helmet. The air gap in between it and his head would provide a nice mismatch, and he would have a handy source of nutrition if on the run.
    Lol, no actually I'm not referring to mind control but there are History Channel documentaries that delve into this subject via radio frequencies like a cell. No I'm only referring to blocking ultrasound via a barrier. As he stated a double window vacuum.
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    Quote Originally Posted by tk421 View Post
    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    You keep asking this question even though you've received many answers. Part of the problem is that your question is vague -- you have not specified any boundary conditions. How is the ultrasound getting to the material? Through air? Some other medium? What is the frequency? Is it a single tone, or does the spectrum occupy a large bandwidth? How much attenuation do you need? And does the material have to be optically transparent? Is weight a factor? Etc. The list goes on and on.

    In the absence of specifics from you, all we can do is point out the following: There are two general mechanisms by which you might block acoustic (or electromagnetic) energy: Absorption and reflection. The former essentially converts the ultrasound energy into heat, while the latter bounces it back to the source or otherwise scatters it. You can, of course, combine these two mechanisms (stealth technology exploits both).

    If the ultrasound is propagating through the air, reflection merely requires a material whose acoustic impedance is very different from that of air. Astromark's vacuum is one example of exploiting that principle. Another is related to the medical ultrasound example that dan hunter mentioned. The acoustic impedance mismatch between air and meat is rather large at the multi-MHz frequencies used in ultrasound imaging, which is why intimate contact using a gel is required.

    You need to be much, much more specific in order to receive any more specific answers. You seem to think that there's a material that automagically solves your problem, but there isn't.
    Air, anything above 20Hz. As fas as weight, anything that comes to mind would be good. I'm looking for as much input as you can give me. Say a freq capable of being felt by human skin. I'm wondering can one layer suffice or does there need to be a vacuum between a duel layered barrier? List how you would go about it the light, and heavy way. Like for example how about duel layered plexiglas or polycarbonate with air inbetween? Can you think of any matetials where one layer might suffice?
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    Quote Originally Posted by dan hunter View Post
    Maybe you need to look at the work done on ultrasound imagery for medical use.
    Ultrasound can be attenuated through absorbtion or even reflected if the difference in the material being probed are high enough.

    I can't give you specific materials that will block ultrasound for several reasons. First is I would need to know if the blocking was to be by impedence or reflection.
    Impedence would mean you wanted to make the surface vanish as far as the probe was concerned, reflection would mean you simply want to hide something behind a clearly visible barrier.

    Next I would need to know the specfic frequency you wanted to block and the sound pressure being used.

    Next I would need a set of material property tables listing the accoustic impedence of the materials.
    Finally I would need to be an actual expert in the field so I could make a sensible recommendation.
    Above 20Hz. Behind a barrier.
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    Quote Originally Posted by astromark View Post
    ~ I can answer your question.. As I have worked with Ultrasound as one of the many tools in our box used for scrutiny of the rock structures of sea bed strata s.. While looking for petroleum bearing structures.. and right through the spectrum to evaluating fault motion history and Volcanic uplifts and vents on the oceans floor.. Mapping of the seabed is a science of considerable complexity that involves many facets of science. You want to know what would screen you from such probing ? A vacuum. Like a double glassed window.
    It will only shield ultra sound.. sound. Other methods of probing the Earths depths and crust are not able to be shielded..
    ' Is this the second attempt at this question..? '
    All sound and electromagnetic waves should be blockable by some mechanism. Say the sound was projected through the air at an intensity to burn, itch, or tingle the skin, and you needed to construct a shield like Captain America to block it would any materials come to mind in such a scenario? And would the shield be duel layered with a vacuum inbetween? What about infrasonic frequencies? Would the same principles apply?
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    Quote Originally Posted by mcriv880 View Post
    Air, anything above 20Hz.
    20Hz is not ultrasonic. Again - earplugs.
    Say a freq capable of being felt by human skin.
    No sounds (below a very intense level) can be felt by human skin.
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by mcriv880 View Post
    Air, anything above 20Hz.
    20Hz is not ultrasonic. Again - earplugs.
    Say a freq capable of being felt by human skin.
    No sounds (below a very intense level) can be felt by human skin.
    20kHz
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by mcriv880 View Post
    Air, anything above 20Hz.
    20Hz is not ultrasonic. Again - earplugs.
    Say a freq capable of being felt by human skin.
    No sounds (below a very intense level) can be felt by human skin.
    FOCAL DESTRUCTION OF NERVOUS TISSUE BY FOCUSED ULTRASOUND: BIOPHYSICAL FACTORS INFLUENCING ITS APPLICATION
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    how about uncoupling the transducer from your head?
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    Quote Originally Posted by fizzlooney View Post
    how about uncoupling the transducer from your head?
    What about bubble wrap?
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    Quote Originally Posted by fizzlooney View Post
    how about uncoupling the transducer from your head?
    https://drive.google.com/file/d/0B-C...it?usp=sharing
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    If you want to block the effect of an ultra sound weapon, the best advise is to get out of range. Also it is time for a reality check. Do you think an unltrasound weapon is being currently used against you? To the best of my knowledge ultrasound weapons are large, bulky and short range. Also they are of very limited effectiveness. If you were being targeted there would be no question, these are big expensive weapons, if someone is using it it is not going to just make you uncomfortable, it is going to kill or incapasitate.
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    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    You may have told us already but indulge me and tell us again: Why do you feel you are being targeted with these mystery weapons?
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    Quote Originally Posted by Chucknorium View Post
    Quote Originally Posted by mcriv880 View Post
    What materials if any are difficult for ultrasound to travel through!?
    You may have told us already but indulge me and tell us again: Why do you feel you are being targeted with these mystery weapons?
    Why do you question whether or not they exist that comes accross as suspicious?

    https://drive.google.com/file/d/0B-C...it?usp=sharing
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    Quote Originally Posted by Sealeaf View Post
    If you want to block the effect of an ultra sound weapon, the best advise is to get out of range. Also it is time for a reality check. Do you think an unltrasound weapon is being currently used against you? To the best of my knowledge ultrasound weapons are large, bulky and short range. Also they are of very limited effectiveness. If you were being targeted there would be no question, these are big expensive weapons, if someone is using it it is not going to just make you uncomfortable, it is going to kill or incapasitate.
    No they are currently incorporated into FBI, CIA, ATF, and DEA field use. You are refering to the LRAD by Raytheon not long range weapons attached to satellites, and antennas.

    https://drive.google.com/file/d/0B-C...it?usp=sharing
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    Quote Originally Posted by mcriv880 View Post
    Quote Originally Posted by Sealeaf View Post
    If you want to block the effect of an ultra sound weapon, the best advise is to get out of range. Also it is time for a reality check. Do you think an unltrasound weapon is being currently used against you? To the best of my knowledge ultrasound weapons are large, bulky and short range. Also they are of very limited effectiveness. If you were being targeted there would be no question, these are big expensive weapons, if someone is using it it is not going to just make you uncomfortable, it is going to kill or incapasitate.
    No they are currently incorporated into FBI, CIA, ATF, and DEA field use. You are refering to the LRAD by Raytheon not long range weapons attached to satellites, and antennas.

    https://drive.google.com/file/d/0B-C...it?usp=sharing
    Are you saying that an ultra sound weapon, that is satellite based, is currently in use, covertly, by agencies of the US government? If so, what effects do you think it has? What damage would we expect to see on the target? What is the range and accuracy?
    I am frankly skeptical about the the actual deployment of this weapon. For one thing no sonic weapon can possibly be satellite based because satelites are in space where sound can't propagate. The souce you refferenced is speculative, discussing thing that may be possible, not things that have been built.
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    Jesus....another ultrasound thread? I already told you in the other thread a "Jello" suit is your best bet.
    Fixin' shit that ain't broke.
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    Quote Originally Posted by MacGyver1968 View Post
    Jesus....another ultrasound thread? I already told you in the other thread a "Jello" suit is your best bet.

    Mmm...Jell-O...

    Damn you, Mac. Now I'm hungry!
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    Quote Originally Posted by mcriv880 View Post
    Above 20Hz. Behind a barrier.
    I think you mean 20kHz; 20Hz is near the lowest sound people can hear, at least half an octave below the lowest key on a grand piano.

    --
    And that paper doesn't mention a single ultrasound weapon, nor more than some exploration done during the 60's,70s...that didn't amount to anything.
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    Quote Originally Posted by Sealeaf View Post
    Are you saying that an ultra sound weapon, that is satellite based, is currently in use, covertly, by agencies of the US government? If so, what effects do you think it has? What damage would we expect to see on the target?
    In a previous post he mentioned that such weapons have been used on him and caused him to lose his hair.
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    So far I see nothing proving his claims are wrong for all we know some mad scientist could be targeting if we don't like the content then we should anwser his question quickly to grave the thread.
    Newbie to Science, trying to educate myself on this forum and further my scientific knowledge.

    I like to ask a ton of questions so please be understanding!

    I like to think of new stuff and in new ways.
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    With thanks to the ' cosmictraveler' who supplied this innovative concept.. The cat does not look impressed..
    "For the deflection of rouge neutrino's 'AND' ultrasound emissions.." The cat will forgive you..
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    wrap your head in garbage which is where this post should end up
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  36. #35  
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    Sound wave belong to mechanical wave with transmitted and propagate through medium by pressure and displacement,
    so to stop it, u need absolute emptiness -- vaccum
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