Sound insulation properties of a spherical structure of subwavelength size

Because of the limited sound insulation provided by a single material, it is common to use multiple layers of materials to improve the effects of sound insulation, but multiple materials increase the size of the model. In some cases, there are limits to the size of the model, or, if subwavelength sizes are required, it is necessary to investigate wideband sound insulation of subwavelength size. We designed a coded topological spherical model on the subwavelength scale, with two materials arranged periodically according to the coding idea. The results showed that at the subwavelength scale, the sound insulation effect of the coded topological spherical model was very significant; the sound pressure after using sound insulation was near 0.3 Pa, but the incident sound pressure was 100 Pa. These results overcome the excessive thickness problem of traditional materials used in sound insulation, which has long puzzled researchers, and expands the application of new sound insulation materials in the energy collection field.