Sounds crazy? Humans can emit the same types of clicks and squeaks bats do – and, with the proper training, determine the size and distance of objects in the environment based on the echoes that bounce back. Larger objects, for example, return louder echoes than smaller ones. Practioners can also gauge whether an object is moving and in what direction that object is moving by the pitch of the echo: if an object is moving closer, than its echo will have a higher pitch than if it is receding.
It might seem odd to passers-by, but proponents claim echolocation gives blind people much more information about the world around them than more traditional navigational aides, such as canes – and thus, more confidence and more freedom. Californian Dan Kish, who heads the group World Access for the Blind, is an expert in echolocation. He has become so adept at it that – despite the fact that he is blind – he can ride a bicycle on public roads.