Helmholtz Resonator

The Helmholtz resonator is a device that involves a rigid spherical container with a small neck. In order to produce sound, it has a specific built. Physically, this device has a small hole in one end and a larger hole in the other. Its name comes from Hermann von Helmholtz. Hermann von Helmholtz, the man who identified the various frequencies and musical pitches present in music and other complex sounds. Its invention came around 1850. 

Just as acoustic boards, reflection filters, and ceiling clouds, this is a soundproofing device.

More on the Helmholtz Resonator’s History

In 1862, von Helmholtz described this device in his famous book named On the Sensations of Tone. He wrote that, when the user inserts a resonator directly inside the ear, most of the tones that the surrounding air produces damp. However, if the user achieves proper tone of the resonator, it in turn generates a sound. For example, any listener can perceive the sounds of the resonator in the tones produced by the whistling wind, the splashing of water, and the rattling of carriage wheels. Both internal combustion engine subwoofers and acoustics frequently use the Helmholtz resonator.

The Helmholtz Resonator Itself

The Helmholtz resonator is contained inside a pipeline which has a gap and a neck. One side of the gap arranges the neck part and communicates it with the acoustic pipeline. It involves a sound-absorbing structure with various spaces. These spaces connect the gap with the acoustic pipeline.

Experts represent the optimal acoustic resistance value of the Helmholtz resonator as follows: Re(Zb)apt. This representation is related to the hydraulic diameter (d), the porosity (phi), the flow resistance, as well as the length of the sound that passes through the spaces within the sound-absorbing structure. Overall, Re(Zb) is the inlet acoustic resistance of the Helmholtz resonator.