Abstract: A wide-band sonar system can be used as a mobility aid by the visually impaired. The system includes an acoustic source and a pair of miniature microphone arrays with frequency-dependent beam patterns designed to mimic the properties of the human ear. Each microphone is preferably mounted near a respective ear of the user. In one embodiment the source has a bandwidth of 30-50 kHz and uses a waveform that preferably optimizes the time-bandwidth product. A heterodyning technique is used to shift the received signal down to the audible range (20 Hz-20 kHz), after which it is presented to the user through open-style earphones. The acoustic source and microphone arrays are mounted on the user's head so that the system will always be aligned therewith—as an example, they may be mounted near the user's ears on conventional eyeglass frames or a similar mounting device.