Whistle pitch derives from vocal tract resonances, not the oral cavity’s Helmholtz resonance

Evidence

Some sources (and almost all Internet sources) incorrectly assign the whistle frequency to the Helmholtz resonance of the oral cavity. However, the vocal tract is necessarily open all the way to the larynx while one is whistling, since air is being supplied by the lungs! In this circumstance, there is no resonance that belongs only to the oral cavity. This assertion is easily checked: form a whistle, then without changing your mouth or lip shape, and while breathing in or out slowly, pop your cheek with your index finger and listen for the lowest frequency mode. Its frequency will be far below the whistle frequency. Now close off the oral cavity with the back of the tongue and compare the frequencies. Since the vocal tract is open to allow the air to pass through the lips, the same vocal tract resonances used in speech somehow must control the frequency of the whistle. — Eric J. Heller, Why You Hear What You Hear- An…, 1324

Categorization

• DEFINE: Corrects the common misconception distinguishing Helmholtz resonance from open vocal-tract resonances in whistling.
• SEED: A hands-on self-experiment (pop your cheek while whistling) could anchor a short explainer on why internet physics explanations of whistling are wrong.
• XREF: Connects to Helmholtz resonator theory of pitch production and to the physics of edge tones and recorder-like flutes. — connects to: Fixed vocal tract whistles hold pitch while cavity-free jets rise in pitch with airflow — Eric J. Heller, Why You Hear What You Hear- An…, 1333; A vocal tract constriction at the mouth forms a Helmholtz resonator; Blowing across a bottle mouth produces a Helmholtz resonance (+1 more)
• corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 1324

Broader Connections

• Fixed vocal tract whistles hold pitch while cavity-free jets rise in pitch with airflow #corroborates (0.90) — Eric J. Heller, Why You Hear What You Hear- An…, 1333
• A vocal tract constriction at the mouth forms a Helmholtz resonator #contradicts (0.80)
• Blowing across a bottle mouth produces a Helmholtz resonance #contradicts (0.75)