DESIGN AND DEVELOPMENT OF TACTILE- AIDS FOR THE DEAF

Abstract

Deaf people, as a result of their personal experience, understand the value of the sense of touch for receiving acoustic information. Tactile sensation is generally taken for granted and most people are really aware of it only when - hurt on receiving pleasure. It is, therefore, not surprising that little attention has been paid to tactile stimulation as a means of giving an awareness of sound. The person who is profoundly deaf, for him, the sensation through the skin is one of the effective methods for receiving the acoustic signal through stimulation. The dissertation deals with vibrational stimulation to the skin of the deaf person using tactile vocoder by which a hearing impaired can distinguish the different frequencies being generated corresponding to different acoustic sources (i.e. from different persons). The audio voice signal has been encoded into different frequencies and these frequencies are being passed on to the deaf person for the stimulation of the skin. The dissertation deals with definition of deafness and its causes and the help available for hearing impaired. In addition to dealing with individual components to generate three different frequencies from three oscillators and amplifying the audio signal at different channels, it also includes the design of vibrotactile aid. More emphasis is given on vibrotactile aid than to electro-tactile aid. The overall amplifier system consists of an instrumentation amplifier. which provides high gain, more stability and very high input impedence. Three iv different frequencies have been generated using highly stable oscillators which give low distortion. Multiplexer has been used for control gate and channel selector. A channel-selector choses the particular channel based upon preference. Darlington transistor pair has been used to drive the vibrotactile device. The performance evaluation of the various configurations of the system has been carried out. Overall the performance of the developed system is satisfactory.