The continuation of this grant combines basic research into the perception of vibrotactile stimuli with applied research evaluating tactile aids for speech communication by hearing-impaired persons. The goals of this program of research are to add to knowledge of the processing capabilities of the tactile system and to provide information leading to the design of improved tactile aids. The combination of basic investigation of tactile psychophysics and perception with the evaluation of tactile aids should yield important insights into how complex patterns are processed by the tactile sense and how such patterns should be presented to obtain optimal recognition of speech. In the basic tactile perception studies the interactions of spatial, temporal, and frequency variations in vibrotactile stimuli are studied to determine their effects on tactile processing of such stimuli. These interactions are examined in a variety of tasks designed to cover the range from simple detection of stimuli to complex pattern recognition. As the experiments progress, stimuli are gradually increased in complexity and made to approximate more closely the types of patterns presented by multichannel tactile speech perception devices, so that experimental manipulations can be related to the performance of such devices. In applied evaluations of tactile aids for speech communication, a number of lines of experimentation are pursued to provide convergent information for improving device design and training procedures. The contributions of tactile aids to both speech perception and speech production skills will be studied, and the effects of long-term use of tactile aids will be examined. In addition, a set of experiments that systematically evaluates specific physical parameters of multichannel tactile devices (e.g., number of channels, location and type of stimulators, processing strategies, etc.) will be undertaken to determine whether the levels of performance presently obtained with such devices can be further improved. The results of these varied lines of research should provide a considerable addition to our knowledge about the processing capabilities of the tactile system, and the application of these capabilities in the perception of speech presented through tactile aids.
