Microprocessor-based hearing aid for the deaf

A speech reception aid that converts speech into text by use of a microprocessor has been developed for profoundly deaf people. The present system automatically recognizes a spoken word and presents the corresponding text visually and tactually. The system, however, restricts the acceptable number of words and speakers. A new tactile mode applying the psychophysical effect of apparent movement was introduced to reduce the presentation time for the tactile symbols. Laboratory experiments showed that subjects recognized three- to seven-letter words immediately after pronunciation when using the visual display, and after about 5 seconds when using the tactile display. The presentation time of the tactile display was taken up primarily by the activating time of the stimulators. In tactile presentation, subjects received sentences composed of three to four words with more than 90 percent recognition accuracy after about 18 trial sessions.