BASIC AND APPLICATIONAL STUDY OF MOVABLE SOUND SOURCE USING DEMODULATED SOUND BEAM DERIVED FROM AMPLITUDE MODULATED ULTRASONIC SOUND.

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This research aimed to support the blind on work of reading CRT.The beamed audible sound wave including voice is projected on a wall and radiated from projected point as a secondary sound wave.The vacal sentence from secondary sound source and the position are correspond to the visual sentence on the CRT.Then, the blind can recognize the sentense and the layout by their audible sense.The results of two years research about this system are as follows1. The beamed audible sound wave was simply formed by parametric array.2. The high adaptability of a electrostatic transducer was shown.3. The concaved screen was shown to be optimum for the reflecting screen by it's focal characteristics.4. The best converting system for audible sound beam was found.5. The optimum beam controlling method for the sustem was found.6. The characteristics of localization of this secondary sound sources was measured and found to be same to that of normal sound sources.7. The possibility of grasping content and layout of sentence on the CRT by auditory sense was found.