Image Number 10 for United States Patent #6671226.
An ultrasonic path guidance system and method for the visually impaired uses an array of ultrasound transmitters that are directional and aimed at distinct locations forward of the user. The transmitters are positioned on the torso of the individual user and one or more receivers detect echoes from obstacles upon which the transmitted ultrasound sound impinges. Audible tone is generated each time an echo is received. The tone's frequency is dependent on which transmitter transmitted the original ultrasound pulse that resulted in the detected echo. This gives an easy to understand indication of the location of detected obstacles. The elapsed time from emission of an ultrasound pulse to reception of its echo is used to arrive at the distance to the obstacle.