Definition
Hi-hat opens and closes describe the two states of a hi-hat: closed for a tight "tick" and open for a longer, washy "tssss", with the foot or a pad controlling the transition between them.
Example
A typical groove plays closed hi-hats through the bar, then briefly opens the hat just before the snare for a short splash that releases tension, snapping it shut again on the next hit. That open-then-close move is one of the most expressive details in a drum part.
Why it matters
The interplay of open and closed hats gives a hi-hat line shape and breath instead of a flat, even tick. On pads, handling opens and closes well, and cutting the open sound off cleanly, is what separates a convincing programmed groove from an obviously fake one.
How to play or configure
Map closed, open, and pedal hi-hats to separate pads and assign all of them to one choke group, so a closed hit silences a ringing open one. Practise placing a single open hat just before the backbeat, then closing it on the next sixteenth. Velocity layers help the closed hat move between soft ticks and firm accents within the same pattern.
Related terms
Further reading
Finger Drumming for Beginners covers hi-hat control for new players.