When you're playing the high hat there are a variety of different techniques and different ways you can play it. There's closed, there's fully open, and then there's also half open. This is called the half open high hat. Really it's just what it says where if you pull your foot off the pedal, the high hat is going to open fully where the cymbals are totally separate from each other. If you use a heel down technique to lightly depress the pedal and gently put the cymbals together, you're going to get a little more of a buzzier sound from the high hat based on the fact that it's now not totally tight and of course not totally open. The cymbals are just resting on each other. The cymbals move a little bit more. You can tell it has a little bit more give, rather than if it was closed, you can't really depress. Of course if it's open, they're totally separate from each other.
Gently pressing on the petal and getting the high hats together, you're going to get the sound that you're looking for. And if you hit the edge of the high hat, it's going to sound something like this. You have a little bit of decay from the cymbals. The cymbals buzz together, but it's enough where it doesn't cut off short the way it would if it's tight and it's not totally open where you hear both of the cymbal sounds. You hear the sound of the two cymbals together. And this is more common in a rock style where you're really playing hard and you'll want to hear the cymbals come out really strong over the top of the music.