Ir. Summers et al., VIBROTACTILE AND ELECTROTACTILE PERCEPTION OF TIME-VARYING PULSE TRAINS, The Journal of the Acoustical Society of America, 95(3), 1994, pp. 1548-1558
To establish the best strategy for transmitting speech-derived informa
tion via a single tactile channel, measurements were made on the perce
ption of frequency-and/or amplitude-modulated pulse-train stimuli, wit
h a comparison of the electrotactile and vibrotactile modalities. In o
ne experiment, vibrotactile perception of 2-oct step changes in stimul
us frequency was found to be significantly better than electrotactile
on a timescale appropriate for the transmission of speech features (e.
g., with practiced subjects, information transfer of 69% with 200-ms v
ibrotactile stimuli, 32% with 200-ms electrotactile stimuli). Percepti
on of step changes in stimulus amplitude was similar in the two modali
ties when changes in amplitude were tailored to match the different dy
namic ranges available. In a second experiment, vibrotactile perceptio
n of voice fundamental frequency with various codings was investigated
. Both experiments showed information transfer for vibrotactile stimul
i to be greater when frequency and amplitude modulation were used toge
ther rather than with one or the other in isolation (sentence-stress i
dentification scores: 66% for FM stimuli, 69% for AM stimuli, 80% for
FM/AM stimuli). It is concluded that frequency- and amplitude-modulate
d vibratory stimulation is a good choice in a practical device for the
profoundly hearing impaired.