Pulling the vocal tract resonance down bends notes but is self-limiting.

Evidence

Figure 10.9 shows that as the vocal tract resonance is brought down from above, the note can be deflected (bent) down farther and farther. However, the process is self-limiting: if the tract resonance becomes too low, the air column component of the mode becomes weaker, and the SPL in the mouth grows larger. Indeed, the trend to increasing mouth SPL for deeper bending is measurable. We have successfully explained why bending notes down on a clarinet or sax is possible, and how it happens. — Eric J. Heller, Why You Hear What You Hear- An…, 1626

Categorization

• QUESTION: The self-limiting mechanism (weakened air column component, rising mouth SPL) — is the mouth SPL rise audible to the player and does it set the practical bend limit?
• XREF: Ties to the coupled-oscillator frequency-shift treatment from earlier chapters and to figure 10.9.