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Why can't we see the sound?

  1. Mar 12, 2015 #1
    i know this is a primitive question and to be answered in my head. eventually both light and sound are a wave carrying information and energy. is speed of light effective to we see it?
     
  2. jcsd
  3. Mar 12, 2015 #2

    DaveC426913

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    We have receptors in our eyes that are excited (chemically altered) when light of a certain wavelength of photons (440-770nm) impinges upon them. That is what we call "seeing".

    The thing we call sound is actually pressure waves of molecules (not photons), usually of air. These waves have wavelengths on the order of metres (millions of times longer than light). Our receptors are not excited by moving molecules (of air or of retinal fluid).
     
  4. Mar 12, 2015 #3
    We do hear sounds. I think that some animals can form a pretty accurate representation of their surroundings using sound. They have suitable sensory organs to do that.
    Due to the different nature of the sound and light waves, we need different organs (sensors) to reveal them (as DaveC426913 said better than me)
     
  5. Mar 12, 2015 #4

    DaveC426913

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    Did you want to edit that question? The OP was not asking about hearing sounds.
     
  6. Mar 12, 2015 #5

    phinds

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    I think you're both right. Franz was speaking somewhat metaphorically and should have said "we do SEE sounds" ... well, not us really but bats for example are known to "see" using sound.
     
  7. Mar 12, 2015 #6
    No I just tried to avoid interpreting too much the question. Perhaps I focused too much on the fact that there is more than revealing photons involved in "seeing".
    I was trying to help, anyway.
     
  8. Mar 12, 2015 #7
  9. Mar 12, 2015 #8

    phinds

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    Well, if you want to go that way, there are tons of light-display things that are sound-wave driven and even an oscilloscope let's you "see" sound.

    I'm pretty sure this is not what the OP had in mind.
     
  10. Mar 12, 2015 #9

    wabbit

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    To some extent humans also form a kind of mental image of their surroundings from auditive cues, and this ability can be enhanced with training:
    https://en.wikipedia.org/wiki/Human_echolocation

    The longer wavelengths of sound impose a limitation to how precise this can be, but sound at say 3000Hz, has about 10cm resolution so it isn't that bad (echolocation relies on clicks which aren't pure frequencies)

    Also the fact that we so not see the auditive image in the same way as a visual one is related to the physical process but also to the brain "post-processing"
     
  11. Mar 13, 2015 #10

    atyy

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    Wow, the Thaler, Arnott and Goodale result on that page is amazing!

    Edit: But were the echolocation experts blind from birth?
     
  12. Mar 13, 2015 #11

    wabbit

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    Some were, others lost their sight during childhood or later. Not sure about those included in that study.

    Edit : From the article :
     
    Last edited: Mar 13, 2015
  13. Mar 19, 2015 #12
    Is it possible for animals that are deaf to see sound since they have more/less receptors in their eyes? Maybe flies? Sometimes when I shout at them they appear to be startled and fly away.
     
  14. Mar 20, 2015 #13

    blue_leaf77

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  15. Mar 21, 2015 #14
    Sound is nothing but vibrations in air. Bass drums move the air so much we feel this with our entire body. But any sufficiently thin sheet of matter, that can vibrate with the air, will be sensitive to sound. Membranes are optimized for this.

    I'm not a fly expert, but I would expect their wings to be so thin that any noise would make them move just enough that the fly senses it. Maybe it's another part of of their body. There is no point in using the word "see". If something is sensitive to air vibrations, we use "hear", sense", or "receive".
     
  16. Mar 21, 2015 #15

    Delta²

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    You are right they are both waves that carry information and energy but they are very different kind of waves. Light is a wave of the electromagnetic field and carries energy of electric and magnetic field. Sound on the other hand is a wave of matter (also referred to as mechanical wave) that carries kinetic energy of the molecules of the medium it is transmitted within (the medium for sound is usually air). Now our eyes can sense only waves of electromagnetic field that have a frequency between 1000-2000TeraHz. It is our ears that can sense mechanical waves in the air with frequency 4hz-22Kilohz. To emphasize it again it is not only the different range of frequencies it is that they are different kind of waves as i said in start. (1kilohz=1000hz, 1Terahz=1000 billion hz)

    helpfull should be the following link, should be enough to read just the intro section http://en.wikipedia.org/wiki/Wave
     
    Last edited: Mar 21, 2015
  17. Mar 21, 2015 #16

    wabbit

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    While this is true, I think the frequency is probably the key difference though : other differences mostly mean that we need different types of sensors to detect them, but the kind of perceptual image we can form depends only weakly on that (and studies of echolocation or synesthesis suggest there is some overlap between the two forms of perception).

    EM waves in the kilohertz frequency range are VLF radio waves - and if we had sensors receptive to these, 'EM sensitive cochleas' so to speak (which we could actually get artificially by using a radio receiver connected to an earphone), we could hear EM waves.

    (Note that while a radio set also converts EM waves to sound, it is differs from such an "EM ear" in that the the sound frequencies it produces do not directly correspond to the EM frequencies received)
     
    Last edited: Mar 21, 2015
  18. Mar 21, 2015 #17
    Sound is a kind of disturbance, right?? It travels by vibrating molecules which can't be seen with a naked eye. So we can't see sound. I don't know whether this is true or not. But that's what my imagination is. I'm just in 9th grade. Please correct me if I'm wrong.
    And I have another thought, sound is not a substance right?? It doesn't have any particles but it solely moves through molecules. Sound is a vibration / disturbance. We can see vibrating bodies but we cannot see vibrations..
     
  19. Mar 21, 2015 #18

    wabbit

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  20. Mar 21, 2015 #19

    DaveC426913

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    Yup. Almost all insects and arachnids are covered in tiny hairs that are sensitive to vibration.
     
  21. Mar 21, 2015 #20

    wabbit

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    Ah yes. If I remember correctly, these are actually quite similar (well, if not they at least perform the same function) to the "hairs" or ciliae that serve to detect sound in the human ear.
     
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