Physics » Sound and the Physics of Hearing » Sound Interference and Resonance: Standing Waves in Air Columns

Summarizing Sound Interference and Resonance


  • Sound interference and resonance have the same properties as defined for all waves.
  • In air columns, the lowest-frequency resonance is called the fundamental, whereas all higher resonant frequencies are called overtones. Collectively, they are called harmonics.
  • The resonant frequencies of a tube closed at one end are:

    \({f}_{n}=n\cfrac{{v}_{w}}{4L}\text{,}n=1, 3, 5\text{.}\text{.}\text{.,}\)

    \({f}_{1}\) is the fundamental and \(L\) is the length of the tube.

  • The resonant frequencies of a tube open at both ends are:

    \({f}_{n}=n\cfrac{{v}_{w}}{2L}\text{,}n=1, 2, 3\text{.}\text{.}\text{.}\)



point of maximum displacement


point of zero displacement


the lowest-frequency resonance


all resonant frequencies higher than the fundamental


the term used to refer collectively to the fundamental and its overtones

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