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Homework Help: How do we hear things?

  1. Sep 10, 2010 #1
    We're doing sound waves in class at the moment, and basically I'm just trying to get a greater conceptual understanding of it by asking the simple question: how does sound get from a musical string, or a pipe into our ears?

    We've done compressions and rarefactions etc, but I don't really understand how the sound actually moves in those waves to get to our ears?

    I would love a sort of summary of how the wave theory is actually applied in this obvious scenario.

  2. jcsd
  3. Sep 10, 2010 #2


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    I may be misinterpreting where exactly you confusion lies, but I'll give it a shot.

    The waves are the sound. The sound is not carried in the waves, sound is what our brains interpet compressive waves as.

    If you used a tiny pair of tweezers to grab your eardrum and wiggle it in and out 60 times per second, your brain would interpret this as a 60Hz hum. Note that you could move your tweezers in complete silence; it is the back and forth motion itself (by tweezer or by air pressure) that we perceive as sound.

    Q: If a tree falls in a forest, and no one is there to hear it, does it make a sound?
    A: No. Vibrations of the air are simply that - vibrations. It takes an ear and a brain to make that into a sound.
  4. Sep 10, 2010 #3
    Thanks, that's actually very helpful, but it wasn't what i meant exactly :)

    Essentially if I was asked this question in an exam, how would you answer:

    A guitar string is plucked, and a man 2m away hears the sound. Explain the process from the sound being created, to it being heard by the man in terms of sound waves.

    Obviously a stupid question that I just made up, but that's basically what I don't understand - how it all fits together.
  5. Sep 10, 2010 #4


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    Last edited by a moderator: Apr 25, 2017
  6. Sep 10, 2010 #5
    Basically I just don't know how I would answer that sort of question -what would your response be if it had to be 3-4 sentences, for example.
  7. Sep 10, 2010 #6


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    Nice try. We cannot do your homework for you.

    Write your ideas, we can help you.
  8. Sep 10, 2010 #7
    as I initially said, this is not a homework question. I can do all of the questions in class/homework questions, I just like to have a bit more conceptual understanding, hence I'm asking for an explanation of the concept here. I just asked for 3-4 sentences in the hope that you would give a more detailed reply, which you seem reluctant to do. Paradoxically however, your reluctance to respond would seem to negate any point to you replying, but who am I to question what you do :)

    I just can't understand the concept! :)
  9. Sep 10, 2010 #8


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    I am not reluctant; I am bound by PF rules.

    And so are you.

    Write what you know, or what you think. We can correct.

    (It would have taken less of your time and less of your writing to do that in the first place rather than repeatedly asking for someone else to write it for you. :wink:)
  10. Sep 10, 2010 #9
    I'm sorry, I don't understand your reasoning? I'm not asking for an answer, I'm asking for an explanation of a concept.

    I have written all that I know 'through compressions and rarefactions' and I was hoping that somebody could explain how this is put into practice for me. How can I write an explanation for you to check, if I don't know the explanation myself, hence I am asking? :)
  11. Sep 10, 2010 #10


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    https://www.physicsforums.com/showpost.php?p=66018", which you agreed to when you signed up.
    Now stop stalling. Just write what you know or think.
    Last edited by a moderator: Apr 25, 2017
  12. Sep 10, 2010 #11

    Math Is Hard

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    Maybe we can back up.

    1) Sound waves travel through the air and enter the ear
    2) The pressure from these waves cause the eardrum (tympanic membrane) to vibrate

    So , my guess is that you might want to know:

    a) What happens before 1
    b) What happens after 2
    c) More clarification about the processes in either 1 or 2
  13. Sep 11, 2010 #12


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    Why not wiki "sound" for a detailed explanation? Then ask away on this forum if you need clarification. BTW, any relation to Joseph Heller?
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