Acoustic Mobility Aid for the Visually Impaired
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.
MOUNTAIN DAVID C [US]; MORLAND CAMERON J [US]
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