“Ordinary people with no special skills can use tongue clicks to visualize objects by listening to the way sound echoes off their surroundings, according to acoustic experts at the University of Alcalá de Henares in Spain. […] Martinez and his colleagues are developing a system to teach people how to use echolocation, a skill that could be particularly useful for the blind and for people who work under dark or smoky conditions, like firefighters – or cat burglars.”