Whistling without the use of an artificial whistle is achieved by creating a small opening with one's lips, usually after applying moisture and then blowing or sucking air through the space. The air is moderated by the lips, curled tongue, teeth or fingers to create turbulence, and the curled tongue acts as a resonant chamber to enhance the resulting sound by acting as a type of Helmholtz resonator. By moving the various parts of the lips, fingers, tongue and epiglottis, one can then manipulate the types of whistles produced.
