Auditory perception and its relation to ultrasonic blind guidance aids

Experiments have been conducted to determine the optimum form of auditory presentation of signals received with ultrasonic echo-location guidance aids. Pulses of tone and continuous-wave frequency-modulated transmission were used, and there was no doubt that the latter form of transmission produced the most suitable auditory signals. A portable guidance aid was made, using frequency-modulation echo-location principles, and the results justify tests with a small group of blind people.