Method and apparatus for application of echolocation to robot guidance and assisting the blind. The method is based on the echolocation of bats. It combines a source of pulsed ultrasound (100) with a recently-developed acoustic vector probe (AVP) (200) into an echolocation instrument (1000), together with a data-acquisition system (300), a digital signal processor (400) and an output device (500). The source emits pulses of ultrasound of about 35 kHz over a beam angle of approximately 100 degrees and the AVP detects backscattered pulses from a discrete distribution of acoustic highlights on surrounding objects. The ultrasonic sound pressures of the backscattered pulses are heterodyned down to lower frequencies so that the signal processor can make an accurate determination of the sound-intensity vector for each pulse. The sound-intensity vector points in the direction of the highlight from which the backscattered pulse originates while the round-trip time of flight of the pulse determines the distance to the highlight. In this way the positions of the highlights on surrounding objects can be determined. The distribution of such highlights changes when the echolocation instrument moves relative to surrounding objects, generating a sequence of highlight distributions that can be stored in the memory of the processor and combined to provide a more complete representation of surrounding objects.