Have you ever tried? I find the article's description a bit too advanced for a first try. I have personally had success finding walls or large furniture after only a couple minutes of very slowly walking around a room and clicking my tongue (higher pitched) with my eyes closed. True, I probably won't ever be able to ride a bike, but it's sufficient to quickly test out basic echolocation. I have done many trials with friends and everyone is able to hear at least a subtle difference when standing directly in front of a wall as opposed to a few feet away.