“…But it was not until 1860 that Helmholtz formulated the first mathematical theory of Helmholtz resonators [9]. One of the directions in the study of Helmholtz resonators is the study of resonances that arise in many problems of mathematics, physics and technology [4,12,14,16,20,24,25]. Although the study of the resonances of the Helmholtz resonator was carried out by Rayleigh [22], it is still relevant.…”