A small resonator at an instrument’s throat shapes its whole spectral envelope

Evidence

We have learned that the overall spectral envelope of the peaks is determined by the “the little instrument at the throat of the big one”—that is, the mouthpiece at the beginning of the trumpet tube. This is about to become an emerging theme. The resonant behavior of some smaller part of the instrument juxtaposing itself between the sound generator and the main body of the instrument is crucial to the flute, clarinet, sax, voice, and the violin family as well. The effect needs a name, to help us recognize its importance and ubiquity. We call it the gatekeeper resonance effect The resonator is always at the throat (gateway) of the instrument, so it acts early and affects the power spectrum shape quite broadly by virtue of early echo and the sculpting principle, as we shall presently explain in the case of the flute cork, and as we just did for the trumpet mouthpiece. There is another consequence of importance for wind instruments: shifts in the positions of the sharper resonances of the whole instrument, resulting from the phase shifting (as much as 180 degrees as the frequency passes from well below to well above the gatekeeper resonance) of the gatekeeper through its resonance. — Eric J. Heller, Why You Hear What You Hear- An…, 1497

Categorization

• DEFINE: Names and defines the gatekeeper resonance effect — a small resonator at the throat of an instrument that sculpts the entire power spectrum.
• XREF: Connects to the earlier trumpet mouthpiece analysis (chapter on brass/wind coming up) and to the sculpting principle and early echo concepts from prior chapters. — connects to: Resonator geometry shapes which harmonics appear in an instrument’s sound — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1228