Subwavelength monopole resonance of a cylindrical void in a soft material (L)

A soft material embedded with resonant inclusions can be tailored for targeted acoustic performance in underwater applications. Voids that are distributed in the soft material exhibit strong monopolar resonance similar to the well-known Minnaert resonance of air bubbles in water. While the resonance of a spherical void has been extensively studied and reported, the analytical treatment of a cylindrical void has been less frequently investigated. Such a void has a lower frequency response than the spherical case and its analysis is more challenging. The aim of this Letter to the Editor is to compare closed form estimations and asymptotic results available in the literature for the monopole resonance frequency of a vacuous cylindrical-shaped void in a soft material and establish the conditions for which the expressions are valid.