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How do we hear things?

  1. Jan 10, 2016 #1
    I know that the audible range is 20Hz to 20000 Hz.... does this mean if give a string a vibration such that it has a frequency of 20Hz... it will cause a vibration in the air with a equal frequency and thus make it audible? Does this also mean that a string with 19 Hz will be inaudible?
     
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  3. Jan 10, 2016 #2

    phinds

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    Human hearing range is nowhere near that sharply defined. Yes, a 20hz string vibration is what we hear as 20Hz. The starting point for degraded hearing at the upper and lower ends is NOMINALLY 20Hz to 20KHz but the actual degradation points vary by individual. As we get older, the upper end starting point in particular drops off. Some people for example will be born with an upper end starting to degrade at 18KHz and dropping off such that they don't hear anything above 20KHZ but when they are 95 the degradation might start at 15KHZ and drop to nothing at 16KHz. These are just made up examples, but you get the idea, I assume.
     
  4. Jan 10, 2016 #3

    Svein

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  5. Jan 10, 2016 #4
    Alright, but you get my point... if an individuals hearing range IS defined to be 20Hz to 20KHz... they he would be able to hear a 20Hz string but NOT a 19 Hz string right? (again... assuming that some arbitrary individuals hearing range is 20Hz to 20KHz).
     
  6. Jan 10, 2016 #5

    phinds

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    Sure, if things actually worked that way then yes that is they way thing would work but my point is they DON'T work that way. Nobody's hearing is such that they can hear one frequency perfectly and a small frequency different from that not at all and no "definition" you create is going to change that fact.
     
  7. Jan 10, 2016 #6

    Svein

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    Wrong. No such hard limit exists. If you look at the curve in post #3, you will see, that the ear is progressively less sensitive below 1000Hz, and the sensitivity decreases fast when you get to about 20Hz. The curves stop at 20Hz and 20kHz because outside these frequencies it is hard to get good aural measurements.
     
  8. Jan 10, 2016 #7
    alright got it.
     
  9. Jan 10, 2016 #8
    understood!
     
  10. Jan 10, 2016 #9

    davenn

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    no, you hear ALL the way down as low as you care to go ... the difference is that from around 20 - 25 Hz and lower in frequency, you no longer hear a tone, rather you hear the individual pulses.
    So at say 1Hz you hear a pulse once a second, at 0.1 Hz you hear a pulse once every 10 seconds

    This is quite easy to experiment with a function generator that has a good low frequency range into a loudspeaker


    Dave
     
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