Reed instruments divide into high-impedance and interactive pressure-valve subclasses.

Evidence

There are three subclasses of reed-pipe instruments with very different pressure-controlled valves: The first includes reed-pipe organs and harmonicas; these have high-impedance reeds with their own strong preferred frequencies (although these do alter somewhat when interacting with air columns; see section 16.8 for a discussion of the bending of notes with the vocal tract). The second and third subclasses have reeds that are more interactive: cane-reed instruments such as the single-reed clarinet, saxophone, and the double-reed oboe and lip-reed instruments including the trumpet and trombone. — Eric J. Heller, Why You Hear What You Hear- An…, 1535

Categorization

• DEFINE: Clarifies the key distinction between organ/harmonica reeds with fixed preferred frequencies versus interactive cane and lip reeds.
• XREF: connects to: Brass instruments operate acoustically as stopped-end tubes driven by lip reeds — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1234