I can do the click, but...I honestly have no idea how I learned how. I start with my tongue pressed firmly against the highest part of the roof of my mouth, snugly against the part where my mouth goes down towards my front teeth. It's pressed tightly enough that some air is trapped in the back of my mouth. The click is made when I release my tongue extremely quickly, to slap into the bottom of my mouth. It's partially caused by how hard my tongue is hitting the bottom, and partially by the air in the back of my mouth being released, and maybe partly by my tongue hitting...the shelf my front teeth are on...on the way down. You need to have just swallowed before doing the click; if you haven't, some spit might splash out as you try it, if it's pooled under where your tongue would normally rest. And that's disgusting. Writing this, I'm realizing I don't know what any of my mouth parts are called! Also, I almost never ever do it in public, because it's quite loud, and the sound is completely unacceptable in polite company. I generally do it to get an idea of rooms I'm in alone, where nobody can guide me around the space, or describe it. So empty bathrooms, hotel rooms, etc. In general, this is a blindism that you shouldn't try and learn on purpose, and that blind students should be discouraged from doing at all. It's never OK in public, and the times you're completely alone are so rare it's not worth knowing.

I don't think that clicking your tongue, for echolocation should be deemed a blindism. Rather, it's a tool to investigate the environment, and when folks are trained, echolocation can be used to successfully navigate the world. Wiki Daniel Kish, or visit World access for the blind (WAFTB) for more info. I wouldn't consider it any more of an annoyance, then tapping a cane, which on some surfaces, sounds pretty obnoxious. If you were tapping across a hotel lobby with a marble floor, people can hear you coming for miles. Sure, clicking your tongue to explore your surroundings sets a person apart, but having shitty or no vision sets you apart as well. It's not like rocking back-and-forth, while rubbing your fists in your eyes, which serves no purpose other than providing A replacement for missing visual stimuli.