Flute resonances are impedance minima while trumpet resonances are impedance maxima

Evidence

Impedance is defined as force over velocity. The velocity at the end of open tubes is maximal on resonances, so the force (supplied by the air turbulence and fairly constant) divided by the velocity will be minimal. Thus the resonance playing frequencies of the flute are impedance minima, whereas they are maxima for the closed-end trumpet. (Recall that pressure nodes, as at the open end of a tube, are motion anti-nodes.) For that reason, the flute spectrum of resonances is often plotted in terms of the inverse of the impedance—that is, the admittance—and playing frequencies are then maxima of the admittance. — Eric J. Heller, Why You Hear What You Hear- An…, 1571

Categorization

• DEFINE: Defines impedance and admittance as they apply to open versus closed-end wind instruments.