Evaluation of improved correction factors for the prediction of Helmholtz resonances

Innovative meta-materials offer great flexibility for manipulating sound waves and assure unprecedented functionality in the context of acoustic applications. Indeed, they can exhibit extraordinary properties, such as broadband low-frequency absorption, excellent sound insulation, or enhanced sound transmission. More specifically, Helmholtz resonators are exploited in several applications aiming to reduce noise transmission. However, the design of acoustic meta-materials with exciting functionality still represents a challenge, therefore there is a huge interest about the conceptualization and design of innovative acoustic solutions making use of meta-material resonance effects. The main target of the present research work is to obtain an accurate prediction of the tuning frequency of a Helmholtz-resonating device, numerically modeled through a Finite Element approach. In this context, an investigation on a correction factor for the classical formulation used to estimate the Helmholtz resonance frequency starting from its geometrical characteristics, accounting for different-shaped resonators with varying neck/cavity ratios is performed. More specifically, a set of analyses are performed, and results in terms of correction factor are provided in both graphical and polynomial form, and compared with Finite Element ones, showing higher accuracy.