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Sound Intensity of a clarinet

  1. Apr 30, 2009 #1
    1. The problem statement, all variables and given/known data
    if one clarinet is playing a note at a sound level of 60 dB, what is the sound intensity of 7 clarinets playing identically at one time?

    2. Relevant equations
    is B=(10dB)log(I/Io) relevant to this?


    3. The attempt at a solution
    I just need to be pointed in the right direction, but its gonna take some pretty obvious hints because I'm brand new to physics.

    Thanks ahead of time.

    Wade
     
  2. jcsd
  3. Apr 30, 2009 #2

    rl.bhat

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    In place of I put 7I write another equation. Compare two equation to find the new intensity level.
     
  4. Apr 30, 2009 #3
    so I should put this:

    B=(10dB)log(I/Io)

    B=(10dB)log(7I/Io)

    so is it 60=(10dB)log(7I/1)??
     
  5. Apr 30, 2009 #4

    rl.bhat

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    No.
    60=(10dB)log(I/Io)...........(1)
    B=(10dB)log(7I/Io)...........(2)
    From equations 1 and 2 find B
     
  6. Apr 30, 2009 #5
    I'm a little confused about how to do it? baby steps please?
     
  7. Apr 30, 2009 #6

    rl.bhat

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    OK.
    You can the eq. 2 as
    B = 10dBlog(I/Io) + 10dBlog7
    Now solve for B
    Or
    From equation find I using Io value. Then find intensity level for 7I
     
  8. Apr 30, 2009 #7
    what is the Io value? is that some standard value that I am missing?

    Maybe that's why this is so difficult...it seems like there are too many variables...
     
  9. Apr 30, 2009 #8
    Would you explain how to solve for B when you don't know the value for I or Io? Also, the question asks for the intensity....so why am I solving for B? and also, isn't B 60?
     
  10. Apr 30, 2009 #9

    rl.bhat

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    Find the definition of dB.
     
  11. Apr 30, 2009 #10

    rl.bhat

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    Then you can do this way.

    From equation find I using Io value. Then find intensity of seven clarinets
     
  12. Apr 30, 2009 #11

    You basically said this already. Is there anything else you can tell me? I looked up the definition for dB and it is basically the equation I have given to begin with. Still not sure how to get Io, or where to put the 60 in order to find the intensity like the problem asks. Please be clear, some of your answers have had typos and it makes it pretty hard to understand.

    thanks again.
     
  13. Apr 30, 2009 #12

    rl.bhat

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    B=(10dB)log(I/Io)
    In the given problem B = 60 dB.
    According to definition of intensity level Io is equal to 10^-12 W/m^2, threshold of human hearing. Here logarithm is taken to base 10.
     
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