Directional Guidance Method for the Blind Using Time Separation Pitch Discrimination of Triple Pulse Signals.

摘要

One of the most difficult problems in orientation and mobility training with blind people is that subjects veer either to the left or to the right while attempting to walk a straight path. This veering tendency is most pronounced when attempting to traverse an open area in the absence of consistent tactile or auditory cues. We propose a training method in which a blind person receives continuous feedback while walking along a predetermined line. This method was designed to allow immediate recognition and correction of deviations from the straight path. The laboratory simulation of the training method involved detecting delays between sound pulses by observing changes in time separation pitch (TSP). TSP is a perceived pitch resulting from hearing at least two highly correlated, broadband pulses. (For example, the pulses could have the same shape or the second pulse could be the inverse of the first). We hypothesized that an observer could follow a line by listening to the TSP perceived from two stationary, spatially separated and synchronized pulse transmitters, one producing the first and third pulses and the other transmitter producing the second pulse, thus forming a pulse triplet. The success of such a direction-finding system for the blind depends on the ability of the subject to recognize deviations from the line and to return to the line. We performed psychoacoustic experiments using signals simulating stimuli that a subject would hear while traveling on or near the line defined by three coordinated pulses.