A study of sensory substitute systems based on biomedical acoustics

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The purpose of this research is to create sensory substitute systems based on biomedical acoustics. The research results are shows as follows.1. A new tactile aide method for the deaf was proposed. In this method, speech spectral patterns were swept on a fingertip as convex patterns for vowels and vibration patterns for consonants. This method was proven to dramatically increase the speech recognition rate.2. An electro-larynx which has a function of intonation control by using expiration pressure was designed for people who have lost their larynx. This prosthesis was found to be very beneficial in producing normal sounding speech. This was developed for practical use in cooperation with an electronic company.3. A tinnitus suppresser which stimulates the cochlear nerves was designed and some effects of the electrical stimulation to the cochlea were made clear. We have implanted the tinnitus suppresser for seven patients. It was proven that they could suppress the tinnitus by themselves whenever the tinnitus appeared.4. The mechanism of obstacle sense of the blind was clarified based on psychophysical experiments. The obstacle sense was found to be explained by the following phenomena : preceding effect, correlation of two sound signals obtained from both ears, and coloration. The findings will be applied to rehabilitation for the blind.5. A voice typewriter was designed for the acquired deaf. In the voice typewriter, 68 Japanese monosyllabic voices were converted into Japanese letters. It's response time was 0.2 sec and the recognition rate was about 96%. The prototype of the voice typewriter was developed about 17 years ago. However, the prototype was too expensive for the deaf to buy. In the research, we could improve on the design of a small and cheap voice typewriter for practical use.