Snare wires add their rattle by vibrating against the lower head when struck

Evidence

The snare drum (or “side drum” in marching bands) has a set of metal wires stretched across its lower head (or “snare head”), which vibrate against the snare head when the drum’s upper head or “batter head” is struck. The snares can be dropped from the snare head by means of a lever to allow the drum to be used without the vibrating snare. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1318

Categorization

• DEFINE: Clarifies batter head versus snare head terminology and the lever mechanism that drops the snares.