The transmission of prosodic information via an electrotactile speechreading aid

Variations in voice fundamental frequency were extracted from naturally produced speech samples and transmitted to an electrocutaneous display consisting of 10 electrodes arranged in a linear array along the forearm. Changes in fundamental frequency were encoded as changes in stimulus location. Speechreading performance, with and without the electrocutaneous aid, was examined for both sentence and connected discourse materials with one profoundly hearing-impaired listener and one normally hearing listener whose hearing was masked. After 20 hours of speechreading training in connected discourse tracking procedure, both subjects showed higher tracking rates and faster learning rates with the aid than without the aid. Results from closed-set sentence-identification tests showed that patterns of intonation, stress, and phrase structure, which are not easily speechread, are readily available with the aid.