Proposal of a new tactile display method of speech signals as a nonverbal communication for the profoundly hearing impaired

We have designed a fingertip tactile vocoder which has a 16×4 vibrator matrix for the deaf. In order to investigate whether or not sweeping display method is useful for recognizing Japanese consonants, vibratory patterns corresponding to the speech spectrum of monosyllables were swept from right to left on a fingertip surface using 4 columns of the vibrator matrix at fixed speeds. The best sweeping velocity was estimated to be 10 cm/sec from the experimental results of the absolute threshold, the two-point threshold and the identification rate of monosyllables. The sweeping display method was shown to overcome the problems such as temporal masking for the consonants, especially for the plosives