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Pitch of sound: Elasticity vs Tension of string

  1. Mar 23, 2010 #1
    Hi there,

    I saw this question in a book. Basically, we are asked to comment on the effects of Tension of a guitar chord and the Elasticity of the chord itself on the frequency of the sound the guitar produces.

    I understand Elasticity will have a positive effect on the speed of sound, and the natural frequency of the chord itself, but will it have any effect on the frequency of sound produced when the guitar chord is struck?

    I fully understand that the bigger the applied tension, the higher pitch the sound will be. But elasticity stumps me...quick frankly.

    Can fellow forummers help me pls? I am a high school Science teacher.... :confused:
     
  2. jcsd
  3. Mar 23, 2010 #2
    Tension is proportional to the elasticity.
     
  4. Mar 23, 2010 #3
    I'm not sure I fully understand the question, but there are 2 ways of looking at this.
    The frequency of the sound the string produces will depend on a) its length, b) tension and c) linear density (mass per unit length)
    Once you have a string on the instrument, you can't change c) so that for practical purposes, the note you get depends only on a) and b)
    You adjust b) to tune up and then it's only a) that matters.
    The elasticity, on the other hand, (Youngs Modulus) depends on the material you use. Steel wires have a higher value than, say, copper. (Though copper isn't normally used!)
    Once you have the wire on the guitar and tuned up, the elasticity of the wire itself doesn't determine the frequency of the note. It does, on the other hand, determine how much you have to turn the tuning key to get the right tension. (Effectively, the extension needed to create the right tension. This is what post 2 above is alluding to.).
    Wires made from different materials (and therefore having a different elasticity) will give the sound produced a different timbre, but that would be difficult to quantify.
    Hope this helps.
     
    Last edited: Mar 23, 2010
  5. Mar 27, 2010 #4
    Thanks Stonebridge for the reply.I see the problem is more of being logically coherent....
     
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