Training in the use of a tactile supplement to lipreading: a long-term case study

The major objective of the study was to evaluate the effectiveness of long-term training for an adult subject fitted with the Tactaid VII vibrotactile aid. A secondary goal of this work was to provide a detailed description of how the KTH Tracking Procedure can be used for training and evaluative purposes.

An adult male subject was fitted with a Tactaid VII tactile aid and provided with weekly training sessions in its use over an 18 mo period. The KTH Tracking Procedure was used for training and to record the subject's performance over time. Additional post-training measures included sentence lists and consonants presented in an [aCa] frame.

The results obtained showed a 19 to 37% improvement in tracking rate when lipreading was supplemented by the Tactaid VII compared with those obtained via lipreading alone. Attempts to supplement lipreading with auditorily presented voicing cues did not result in improved performance. At the completion of the training program, additional tracking measures were obtained with an unfamiliar female speaker. The results of this testing again showed enhanced performance when the Tactaid VII supplemented lipreading. Post-training testing with sentence materials yielded scores of 29.8% correct for lipreading alone and 39.9% correct for lipreading plus the Tactaid VII. The subject's scores for consonants in [aCa] testing were 47.0% correct for lipreading alone and 60.1% correct for lipreading plus the Tactaid VII.

The study showed that the use of the Tactaid VII resulted in improved lipreading performance for a range of materials and with two different speakers. The results also highlight the value of the KTH Tracking Procedure for testing and training purposes.