INFORMATION FROM TIME-VARYING VIBROTACTILE STIMULI

Experiments have been carried out to investigate the information trans fer available via a single vibrator on the fingertip. In a first exper iment, for stimuli with durations 80 to 320 ms, discrimination of a on e-octave step change in frequency at the halfway point was investigate d. Results were similar for three stimulus types-sinewave, monophasic pulse and tetraphasic pulse-suggesting temporal cues are more importan t than spectral cues in this task. In a second experiment, subjects we re required to perceive changes in a sequence of stimulus elements. A presentation rate of 6.25 elements s(-1) was found to give better resu lts than a rate of 12.5 elements s(-1). In the former case, the potent ial information transfer per element was estimated to be approximately 1.0 bits, corresponding to an information transfer rate of around 6 b its s(-1). Implications for the design of a tactile aid to lipreading an discussed. (C) 1997 Acoustical Society of America. [S0001-4966(97)0 4111-8].