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Homework Help: Frequency and a pipe organ

  1. Dec 2, 2007 #1
    1. The problem statement, all variables and given/known data
    You are playing a pipe organ, with pipes that are designed to be closed at one end, when you notice that one of the notes sounds wrong. You soon discover that one of the pipes has a hole in the end that was supposed to be closed.
    (a) After you patch up the hole, what will happen to the frequency of the note played by this pipe? Be as specific as possible.
    (b) What else can you do to “tune” an organ pipe (i.e. change the frequency of the notes it plays) without altering the physical construction of the pipes? Indicate how you could increase the frequency of the note and also how you could decrease the frequency of the note.

    2. Relevant equations

    3. The attempt at a solution
    My guess is that the frequency would increase with the hole closed up, but I'm not sure how to explain that. For the second question, I was thinking changing the room temperature would affect the speed, which in turn would affect the frequency, since the wavelength should remain the same.
  2. jcsd
  3. Dec 2, 2007 #2


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    A pipe closed at one end will produce waves that have a node at the closed end and an anti-node at the open end at its fundamental frequency. A pipe open at both ends has a node in the middle and an anti-node at the open ends.

    Temperature is a way you can change the frequency without changing the pipe physically.
  4. Apr 8, 2008 #3
    After the hole is closed, the frequency will be lowered. There are pipes in organs that are partially stopped (i.e. Chimney Flute) that have a "hole" in them.

    Tuning methods: adjusting stoppers at the end of a stopped/partially stopped pipe, adjusting tuning collars attached to the top of the pipe, adjusting tuning scrolls on the back of a pipe (a scroll of metal cut but still attached to the rear of the top of a pipe), or adjusting the resonating length of a reed (reed pipes). All of these methods alter the pitch of a pipe without altering the actual pipe. Cone tuning is a tuning method that alters the actual pipe opening to change pitch.
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