The "acoustic Lazarillo" is a system that gives independence to a blind person to move normally.

The system has two motion sensors: one conditioned on the sunglasses that measures the distances of the blind person to other persons or objects placed before him, and the second, put on a stick that serves to identify potential gaps, steps, etc. , and also to measure at will in other directions. The system also with a converter of the distances quantized by the motion sensors to pulses of sound that will be sent to a wireless headset located in the ear of the blind person.

The frequency of the pulses is directly related to the distance to objects, so the closer you are something to the person, the greater the number of pulses that will listen. By contrast, the cane, when in "stick mode" only give a warning if there variations in the floor.
This system and its use requires prior training.