A driven tube emits at the drive frequency regardless of its own resonances

Evidence

The partials of such a tone are not the same as the resonances of the tube of the instrument To make this clear, note that any one of the tubes we have just discussed could be fed a complex periodic tone at one end, and the tube would have no choice but to emit sound at the equally spaced frequencies of the driving tone. Granted, the tone would be colored by the resonances of the instrument (the strengths of the partials would be affected by the tube resonances—for example, louder if one of them fell on a resonance), but the periodicity of the note would be unaffected. This point goes back to driven oscillators: they always settle down at the drive frequency, whether they like it or not, but their amplitude response depends on the frequency of the drive and how close it is to the resonance of the oscillator. — Eric J. Heller, Why You Hear What You Hear- An…, 1477

Categorization

• DEFINE: Draws the crucial conceptual distinction between the partials of a driven tone and the resonances of the instrument tube.