I thought I'd chime in on the hissing discussion because I figured you guys might like it from a females POV.
As mentioned above, there are many many different kinds of streams, everyone is unique. Having peed next to a lot of women in the adjacent stall I can say that some hiss, and some don't, and even these hisses are all different. Some I'll hear the hissing along with splashing as it hits the water, while others I'll only hear a loud hiss. While with some women I'll hear nothing but a tinkle from them.
As for myself, it depends on how badly I need to pee. I definitely fall into the "silent" category unless I'm bursting for a wee. I'll usually make no noise except for the delicate tinkle as my stream hits the water below, and I really like that. If I'm bursting though, I'll hiss for a little while until the pressure drops a little and then I'll go back to my normal, quiet wee. I can cause myself to hiss however, if I push and force the stream out. I get pee shy occasionally but other than that I never really have any problems fully emptying my bladder, unless , again, I'm desperate. Then I tend to start and stop to get the last drops out.