A Helmholtz Resonator Is A Rigid Container Essay

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A Helmholtz resonator is a rigid container which has an opening to the air surrounding it. A common example of a Helmholtz resonator is a bottle because it has a set volume as well as having an opening which is open to the surrounding air. By considering the Helmholtz resonator as having a neck, such as the neck of a wine bottle, the dynamics of the system may be described. When energy is introduced near the opening of the bottle, for example blowing across it, some of the energy will vibrate the cylindrical plug of air inside the neck of the bottle. This plug of air is assumed to move as a unit. This movement is due to the driving force of blowing across the bottle, the elastic force on the inner end of the plug, and the dissipation force. The top of the air plug acts as single source when it oscillates and will create sound waves. This vibration of the air is due to the springiness of the air. When the air plug is compressed by blowing across the top it increases the pressure inside the bottle and then it bounces back to its original volume. The frequency at which the air inside resonates is unique to the shape of the bottle and depends on the length of the neck, the diameter of the opening and the volume of the bottle. No matter how much energy is introduced, such as blowing soft or hard across the opening, the bottle will produce the frequency which is unique to it.
Theory
To create a useful equation to estimate the resonance frequency of a bottle, three forces must be…