Early horn theories wrongly attributed amplification to wall vibration.

Evidence

Both Kircher and Mathew Young (1750–1800) after him tried to explain how the speaking trumpet worked. Apparently unaware of Ṣafī al-Dīn’s description, they both missed the mark, going too far in implying that vibrations of the walls of the speaking trumpet were important and played an active role in amplifying the sound. However, if they had understood the self-amplification of reflections off perfectly rigid nearby walls, they would have been right. — Eric J. Heller, Why You Hear What You Hear- An…, 571

Categorization

• XREF: Connects to chapter 4’s discussion of sound reflection and early knowers like Ṣafī al-Dīn who described the mechanism correctly.
• corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 571