Resonance in Bottles with Different Shapes

The Helmholtz Resonance equation derived in the 1800’s describes the nature of resonance in narrow-necked vessels, known as Helmholtz Resonators. It is commonly accepted that when air is blown across the opening of a bottle, the resonance can be modeled by the Helmholtz equation. Resonance was studied in two differently shaped bottles as the volume of the air cavity was varied. It was found that resonance in one of the bottles was accurately modeled by the Helmholtz equation but not in the other.