Reconsideration of the Principle of Sound Resonance in Human Whistling Using the Vocal Tract Model

Pucker whistling, achieved via lip puckering, is the most widely used whistling type. Whistling principles in relation to pronunciation are based on Helmholtz resonance. However, certain whistlers can produce high-register sounds by increasing the blowing intensity without changing the capacity of the resonance chamber, similar to the production mechanism of a high-register sound in a wind instrument based on air column resonance. This phenomenon does not occur in Helmholtz resonance. Incidentally, hollow whistling has a fundamental frequency of approximately 400 Hz, which is lower than that of pucker whistling. It is used in human beatboxing, wherein the lip opening is wider than that in pucker whistling. This study aimed to reconsider the principle of sound production in human whistling using human vocal tract models whose plates replace each other while retaining the capacity. Comparisons of experimental results with theoretical values reveal that the resonant frequency of the pucker whistle is close to the formant frequency, whereas that of the hollow whistle is close to the Helmholtz resonance frequency.