Mouthpiece geometry permanently sculpts instrument tone via early echoes

Evidence

The volume of the mouthpiece has to be very close to the missing volume of the cone that it replaces, and the shape matters as well. The inside-out magic at the end of a cone, as described in section 16.2, can easily be ruined by bad geometry, with drastic results on the spectrum of the instrument. Imagine, for example, truncating the apex of a cone and fitting it to a straight section of tubing. There would be some reflections at the joint between cone and straight section, but the real problem is that a wave that made it beyond the joint would not reverse sign as it reflects off the closed end of the straight section of tubing. The impulse response, supposing the impulse is created by a snap of the reed, suffers very early reflection and confinement due to the mouthpiece chamber, which in turn leads to early echoes that are forever sculpted into the spectrum as broad undulations. — Eric J. Heller, Why You Hear What You Hear- An…, 1603

Categorization

• QUESTION: The ‘gatekeeper resonance effect’ recurs here — worth tracing how it unifies across trumpet and sax.
• XREF: Relates to the ‘sculpting principle’ and impulse-response thinking from earlier sound chapters on how geometry shapes spectra. — connects to: Instrument makers shape bore profiles to tune woodwind modes around tone holes — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1225; Resonator geometry shapes which harmonics appear in an instrument’s sound — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1228