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Loudspeaker Design

  1. Mar 2, 2008 #1

    I've just done a bit of reading on some simple loudspeaker design in my textbook. It is asking me to calculate when the first minimum occurs. I think I am fine with this, but my problem is that I have no idea how I would calculate the angle at which the minimum occurs.

    I will use an example given in the book. The sound frequency is 0.14 m and this is emitted by a loudspeaker of diametre 0.15 m.

    I am using the equation:


    I would therefor say that the first minum occurs at [tex]\frac{0.14}{0.15}=0.93 \degrees[/tex]

    The book however says that the angle at which the minimum occurs is about 69 degrees. Could someone please clear this up, it is probably a misunderstanding of some sort. I have not offered working as I do not know the method in solving this, but any help would be great.


  2. jcsd
  3. Mar 2, 2008 #2


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    I'm assuming you meant to say wavelength??

    It looks to me like you just didn't finish the calculation. Use your calculator to compute the angle.
  4. Mar 2, 2008 #3
    Yes, sorry I did mean wavelength. What do you mean I didn't complete the calculation? Are you saying that I have the correct equation to give me that answer?
  5. Mar 2, 2008 #4


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    You have [tex] \sin\theta = \frac{0.14}{0.15} [/tex]

    Solve for theta and you should get 69.0 degrees.
  6. Mar 2, 2008 #5
    :blushing: I can't believe I missed that...

    Thanks for your time. :tongue:
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