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Thread: Which is better for an Ultrasound proof hat(.2-8.0kHz, 135-140dB) Polymethylmethacrylate or Polycarbonate, and how thick must the helmet be?

  1. #1 Which is better for an Ultrasound proof hat(.2-8.0kHz, 135-140dB) Polymethylmethacrylate or Polycarbonate, and how thick must the helmet be? 
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    Which is better for an Ultrasound proof hat(.2-8.0kHz, 135-140dB) Polymethylmethacrylate or Polycarbonate, and how thick must the helmet be? I need someone to construct one coated in lead and silver, and it must cover most of the head like a Vader Mask!


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    Quote Originally Posted by mcriv880 View Post
    Which is better for an Ultrasound proof hat(.2-8.0kHz, 135-140dB) Polymethylmethacrylate or Polycarbonate, and how thick must the helmet be? I need someone to construct one coated in lead and silver, and it must cover most of the head like a Vader Mask!
    Ultrasound is not 200-8000Hz. That's just regular sound. Earplugs or headphones would be a better choice than a helmet.


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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by mcriv880 View Post
    Which is better for an Ultrasound proof hat(.2-8.0kHz, 135-140dB) Polymethylmethacrylate or Polycarbonate, and how thick must the helmet be? I need someone to construct one coated in lead and silver, and it must cover most of the head like a Vader Mask!
    Ultrasound is not 200-8000Hz. That's just regular sound. Earplugs or headphones would be a better choice than a helmet.
    8000Hz is not equal to 8kHz
    .0008Hz I think right? 1000kHz is 1Hz
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    I sorry you are correct I was misreading a chart I was looking at I think the 8000Hz was the adjustment of frequency used in the experiment. The chart just states Ultrasound so if it's above 20,000 it doesn't specify the exact number.
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    8mHz
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  7. #6  
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    Quote Originally Posted by mcriv880 View Post
    8000Hz is not equal to 8kHz
    Yes it is. 8000Hz is 8 thousand hertz. A kilo is a thousand.

    .0008Hz I think right? 1000kHz is 1Hz
    No. 1000kHz is a thousand thousand hertz, or a megahertz (1 MHz).

    0.0008Hz is 0.8 millihertz (0.8mHz), or 800 microhertz.
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    Quote Originally Posted by mcriv880 View Post
    8000Hz is not equal to 8kHz
    Yes, it is.
    .0008Hz I think right?
    That's infrasound, and would be equivalent to 2 cycles per hour. If you sit in an office and someone opens and closes a door twice an hour, that's the frequency they would generate.
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    Quote Originally Posted by billvon View Post
    Quote Originally Posted by mcriv880 View Post
    8000Hz is not equal to 8kHz
    Yes, it is.
    .0008Hz I think right?
    That's infrasound, and would be equivalent to 2 cycles per hour. If you sit in an office and someone opens and closes a door twice an hour, that's the frequency they would generate.
    Wow I never even thought of a frequency like that, I mean it seems obvious the frequency could be very slow, but I haven't even though of twice an hour and that great analogy.

    So you would say the frequency of that door is X

    Wow, so if you were very sensitive to sound you could tell the difference in sound of 3 per hour and 2 per hour?

    It would be slightly higher pitch?
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    No, they'd be the same pitch. You wouldn't be able to discern frequencies that low.
    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 ScienceNoob View Post
    Wow, so if you were very sensitive to sound you could tell the difference in sound of 3 per hour and 2 per hour?

    It would be slightly higher pitch?
    If you could hear them, yes. The energy in such signals is very low, though, so you would need VERY sensitive instruments.
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