The player’s mouth cavity resonates with the instrument and shapes its timbre

Evidence

The effect of vocal tract resonances on the timbre of the trumpet is not huge but not ignorable, either (see section 16.8 for further discussion on this point). There is no doubt that the lips are interacting also with vocal tract resonances, even if the trumpet proper is the dominant effect. The trumpet is a blown open reed instrument (pressure from the player’s mouth tends to open the lip reed). Blown closed reed instruments (pressure from the player’s mouth tends to close the reed) such as a clarinet are thought to be much more influenced by tract resonances; the tuning of these resonances to the note being played by experienced players has been documented (see especially section 16.8.) — Eric J. Heller, Why You Hear What You Hear- An…, 1564

Categorization

• DEFINE: Defines opened vs closed reed instruments by whether mouth pressure opens or closes the reed.