Evaluation of the Siemens Minifonator vibrotactile aid

The Siemens Hearing Instruments Minifonator, a single-channel, wrist-worn vibrotactile aid, was evaluated in a laboratory setting with hearing-impaired adults. Eight subjects, with hearing loss greater than 70 dB in the better ear, were administered a test battery including sound-field detection, speech awareness threshold, environmental sound identification, syllable rhythm and stress categorization, and sentence identification subtests. Performance on each subtest was compared for hearing-aided and tactile-aided conditions. Mean performance levels for the two conditions were comparable for all but one subtest. However, closer inspection revealed that the data for the hearing-aided condition were bimodal: some subjects proved to be good hearing aid users and other performed at chance levels with their hearing aids. Performance in the tactile-aided conditions did not show such variability and mean levels fell between the hearing-aided levels for "good" and "poor" hearing aid users. The effects of training with the device were assessed for two normal-hearing subjects, who were trained in 1-hour daily sessions over a several week period on the environmental sounds and syllable rhythm and stress subtests. Results indicated substantial improvements in performance over the course of training. The implications of these results for long-term use of the device are discussed.