Resonators amplify quiet near-field vibrations far more than direct air-column strikes.

Evidence

The total amount of energy one can typically put directly into the air column resonance (by, say, striking the tube with a cupped hand) is much less than can be put into the mechanical motion of the tube and tongue with a sharp knock. Therefore, the strategy is to put the energy into the tongue vibration and then sit back and let the NFC mechanism feed the near-field energy of the tongue flexure into the tube mode. The coupling between the two is through the air—that is, capture and reradiation by the tube of the near field of the dipole created by tongue oscillation, not some sort of driving of the tube mode by the slight oscillation in the tube itself. — Eric J. Heller, Why You Hear What You Hear- An…, 1908

Categorization

• DEFINE: Clarifies that NFC coupling is an acoustic near-field capture-and-reradiation process, not direct mechanical driving of the tube.