A cone must reverse pulse sign to match an open tube’s resonance period

Evidence

An open-end tube switches the sign of a pulse upon reflection. From the impulse response perspective, the arrival time and the sign of the returning pulse must be the same for an open end and a cone; otherwise, the period would be different. The cone must somehow reverse the sign of the pulse, just like an open end. — Eric J. Heller, Why You Hear What You Hear- An…, 1462

Categorization

• DEFINE: Sharp logical constraint tying impulse-reflection sign to resonance period — a clean derivation-style argument.