“Development and Validation of Theoretical Model for Directional Radiation of Low-Frequency Sound from a Vibrating Cap on a Rigid Sphere”

https://pubmed.ncbi.nlm.nih.gov/38112486

This study develops a theoretical model for the directional radiation of low-frequency sound from a vibrating cap on a rigid spherical shell with a circular aperture, predicting dipolar radiation at very low frequencies, monopolar radiation near the Helmholtz resonance, and increasing directionality at higher frequencies, which is validated through experimental results.