Spherical Harmonics in a Whistle

When air is blown strongly through a straw and across a hole in a hollow sphere, a high-pitched whistling sound is heard. This paper tests two models, Helmholtz Resonance and Spherical Harmonics, to determine which most accurately models this phenomenon. This was done by measuring the frequencies produced when air was blown across identical spheres with different hole sizes, as well as across spheres of different volumes with identical holes. The frequencies were found to closely match frequencies predicted by spherical harmonics.