Multimodal user interface system for blind and "visually occupied" users: ergonomic evaluation of the haptic and auditive dimensions

An ergonomical evaluation of a multimodal windows-oriented interface that gives blind and "visually occupied" persons access to graphical user interfaces. Physical models are used to represent interface features providing haptic informations, thanks to a force-feedback device, and nonspeech audio. In the absence of vision, both auditory and haptic modalities are used, to perform manipulation tasks. Three conditions were compared: sound feedback alone, force feedback alone and bimodal feedback. Measures of usability were timing, error rates with subjective satisfaction. Results from the experiment show that multimodality was associated with better performance for blind and sighted subjects and that it is ranked as the best interface.