Calculate the resonant frequency of a Helmholtz resonator (e.g., a bottle, bass trap, or intake manifold).
Geometric Parameters
Liters
cm²
cm
m/s
Resonant Frequency
Enter geometry to calculate frequency
About this calculator
Quick Reference
vSpeed of Sound
ANeck Area
VCavity Volume
LNeck Length
rNeck Radius
Overview
A Helmholtz resonator is a container of gas with an open hole. When air is forced into the cavity, the pressure inside increases. When the external force is removed, the higher-pressure air flows out, creating resonance.
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Pro Tips
The resonant frequency depends on the geometry of the neck and the volume of the cavity.
The formula includes an 'end correction' for the air moving just outside the neck.
Speed of sound in air at 20°C is approximately 343 m/s.
This model is valid when the dimensions of the resonator are small compared to the wavelength.
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Fun Facts
"Blowing across the top of an empty bottle is the most common example of Helmholtz resonance."
"Acoustic bass traps in recording studios are often designed as Helmholtz resonators."
"The 'thumping' sound when one car window is cracked at high speed is a low-frequency Helmholtz resonance."
