Role of a Multichannel Electrotactile Speech Processor in a Cochlear Implant Program for Profoundly Hearing-impaired Adults*

Abstract

Four profoundly hearing-impaired adults who did not meet current selection criteria for implantation at the University of Melbourne were each fitted with a wearable multichannel electrotactile speech processor (Tickle Talker). The subjects were evaluated with a test battery of speech discrimination tests subsequent to training in use of the device. Thresholds for detection of pure tones were lower for the Tickle Talker than for hearing aids across the frequency range 250 to 4000 Hz. Mean speech detection thresholds for the Ling 5-sound test showed that all sounds were detected by users of the electrotactile device at normal conversational speech intensity levels. Mean speech discrimination scores were significantly higher (p < 0.05) in the tactually aided condition as compared with the tactually unaided for identification of vowels and consonants, on open-set words, open-set sentences, and on connected discourse tracking. Mean scores increased by 20% for vowels, 19% for consonants, 30% for open-set words, and 25% for open-set sentences when the Tickle Talker was used in a multimodal combination with lipreading or lipreading and hearing aids. Speechtracking rates for three subjects showed increases of from 18 to 28 wpm when the tactile device was used. Comparison of tactually aided versus unaided tracking rates for two subjects with long-term experience shows continuing improvement with additional experience with the device. These results demonstrate that hearing-impaired adults not meeting selection criteria for cochlear implantation may benefit from use of an electrotactile speech processor, and highlight the potential benefits from integration of such devices into cochlear implant programs for profoundly hearing-impaired patients.