To communicate with each other we use our voice and ears. Sometimes, in noisy situation, like outdoor, or at broker's office, we can't hear each other, therefore we start speaking on heightened voice.

Have you heard about the extra sense of man, which can read our thoughts? I think, yes. And seen many fantastic movies, where super-heroes could communicate with each other by thoughts.

So, I think that in the near future all the humans will have such ability, cause in 2012 through 2039 the humanity will step on the next stage of evolution.