Attack—essentially the rate and intensity with which a note rises in volume from its point of creation—is one of the coolest musical expressions you can mess with. If you play an instrument from the violin family it’s a fundamental part of your vocabulary. It’s used frequently in synthesis to conjure spooky, low-gravity atmospherics, and it’s an essential tool for taking the front end off some psychotic Moog sound that might otherwise explode like a foghorn six inches from your ear.