Two sounds I dislike to hear when working on hydraulic components are "sproing" and "ting." Sproing comes when a valve or multi-piece component is being disassembled. Just as you give the threaded portion a final twist to clear the threads, there's a blurb of oil which makes you jerk back to avoid an oil bath, and then you hear the sproing as one or more spring-loaded components launch themselves into low earth orbit. Exactly where they were installed, and in what order they were compressed between other pieces, is thereafter anybody's guess, but you darn well know that if you don't reinstall them exactly in that unknown configuration, your repairs are for naught.
The other sound I dislike hearing during hydraulic disassembly is "ting." It's often in association with sproing, but ting signals a very small orifice or flow-control washer has landed somewhere on the floor of the shop. Actually, "ting" at least warns you that a very small piece has escaped your awareness. Without the "ting" it's possible (actually, probable) to reassemble the hydraulic valve or cylinder not knowing that the orifice has gone missing. At least until you activate the hydraulics and the corn head, sprayer wing or other component starts leaping up and down at warp speed rather than as sedately as the engineers designed it to move.
So that's why when I'm working on hydraulics, I unscrew fittings and components very, VERY slowly and watch very, VERY closely the order in which things come apart. At least until a "blurp" catches me off guard and causes a sproing, a ting, and several #@!%!