A fipple tuned by a variable resonant cavity yields a wide pitch range

Evidence

The fipple has no strong natural frequency of its own, and thus the resonance can be tuned over a wide range, depending on the player’s adjustment of the oral cavity and the opening at the lips. — Eric J. Heller, Why You Hear What You Hear- An…, 1310

Categorization

• XREF: Connects to the nose flute / ocarina mechanisms from earlier in the chapter and to Helmholtz-resonator physics generally.
• SHARE: A good extra detail for a musician or acoustics-instrument builder into the physics of fipple instruments.