The long-term goal of this research is to develop tactual aids for persons who are profoundly deaf or deaf-blind to serve as substitutes for hearing in the reception of speech and environmental sounds. This research can contribute to improved speech reception and production, language competence, and environmental-sound recognition in such individuals. The research proposed here is designed to lead to improvements in tactual stimulation systems through two major areas of work: (1) Work in the first area, basic studies of human touch, is designed to increase our knowledge concerning the transmission of information through the sense of touch. One component of this work includes theoretical and experimental studies designed to increase our understanding of the capabilities of the tactual system for dynamic information transfer. The second component of the work in this area includes studies designed to increase our understanding of the psychophysical properties of touch in the scientific design of tactual displays for a broad class of applications, including sensory aids for the deaf. Perceptual interactions will be examined using the following experimental paradigms: temporal-order resolution, masking, roving-level discrimination and identification, and transfer of training. (2) Work in the second area, tactual displays of speech and environmental sounds, is concerned with the application of tactual displays to sensory aids for persons who are profoundly deaf or deaf-blind. Research related to speech includes studies related to the processing and display of envelope-based speech signals through a multifinger tactual display, training and evaluation in the use of such signals as supplements to speechreading, and the development of a desktop multifinger display. Research related to environmental sounds includes studies related to the development and evaluation of signal-processing and display schemes specific to such sounds, as well as a survey of the deaf community (including the signing as well as the oral community) to determine interest in simple tactual aids for detection and recognition of environmental sounds.