Sensory Aids for the Blind Using Acoustics

Abstract

Blind people long have used acoustic cues and echoes, plus oral descriptions or reading, Talking Books, or recordings. To supplement a long cane or dog, an experimental ultrasonic sensor warns of objects at chest height. Binaural ultrasonic “spectacles” sense the environment and aid mobility. A laser cane using optical triangulation provides audible signal of overhead objects, major drops, and objects ahead of the user. LED “spectacles” provide audible warning of an object at head height. The ultrasonic spectacles provide comprehensive but complex signals; the other devices provide go-no-go information. For reading, the latest direct translator of letter shape to tone patterns is a portable, relatively inexpensive stereophonic aid, with bass boost in the left ear and treble in the right. A more complex optical character recognizer, also intended for individual ownership, uses spelled-speech output, coalescing into wordlike groups at higher speeds. Synthesis of easily understood English speech from letter recognition, automatic grapheme-phoneme dictionary, and rules for intonation and inflection will require computer-based library-type operation. These experimental devices have reached user trials. Further clinical studies and education of teams in prescription and training methods should lead to wide use.