Vibrotactile Sensory Substitution for Auditory Speech Communication

Sensory substitution is a concept that has a long history in terms of attempts to ameliorate sensory deficits among people with profound hearing losses. Attempts to substitute touch for hearing predate the age of electronics. In the 20th Century, many attempts have been made to develop sensory substitution systems that transform acoustic speech signals to vibrotactile speech signals. Work in this area may have some implications for the area of haptic interfaces for virtual environments and telerobotics. In this paper, historical developments in tactile speech aids are briefly described as well as a some generic designs for tactile aids. We report on a new wearable tactile aid that transforms acoustic speech signals into vibrotactile signals that convey voice fundamental frequency (F0) information. Two different versions of this device were tested. Subjects were deaf adults. Subjects demonstrated more accurate speech perception with the aid than without. However, effects were smaller than are theoretically possible. Factors that likely contribute to the efficacy of sensory substitutes, including tactile speech aids and haptic interfaces, are discussed.