A discrimination ability of time sequential signal by electrical stimulation to auditory nerves and its comparison with that by vibrotactile stimulation

An experiment on the discrimination of time sequential stimuli of auditory nerves was carried out, and its result was compared with results for the vibrotactile sense. An extracochlear prosthesis that stimulates via an electrode superficially placed on the round window membrane of the cochlea is described. A new speech coding method is proposed for the prosthesis, for transmitting the pitch signal and the second formant frequency. In this method, an additional stimulation pulse is inserted among the pitch pulses, and the time delay from pitch to additional pulse is proportional to the second formant frequency. This coding method has been seen to be effective in recognizing about 60% of Japanese vowels.<
>