Coupling a reeded air column to the vocal tract splits into two shifted modes.

Evidence

We might worry that we now face a three-resonator problem: vocal tract, reed, and air column. Indeed, we do have all three, but we have just dispensed with the unplayable combinations of the coupled reed plus air column. This means that we need consider only the mostly air column mode corresponding to case a in figure 10.9, taking it as a single unified resonator. This resonator is to be coupled to the vocal tract resonator. We proceed down a familiar path: couple two resonators, get two new resonance modes of shifted frequency. In this case, one will be mostly reed and air column and one mostly vocal tract resonance. — Eric J. Heller, Why You Hear What You Hear- An…, 1623

Categorization

• DEFINE: Frames the sax/clarinet as two coupled resonators (air column + vocal tract) whose coupling produces two frequency-shifted modes.