Development and preliminary evaluation of an earmold sound-to-tactile aid for the hearing-impaired.

A binaural earmold sound-to-tactile aid was constructed by inserting a vibrating element into a Lucite earmold. The earmold could be vibrated at either 80 Hz (when incoming acoustic signals were below 2000 Hz), at 300 Hz (when incoming acoustic signals were above 2000 Hz), or both (when incoming acoustic signals were broadband). Subjects were fitted with one of these bimodal vibrating earmolds in each ear. Normal-hearing and hearing-impaired subjects were tested in three tasks: sound localization, environmental sound identification, and syllable rhythm and stress. The device provided some benefit to performance, although the amounts of improvement varied across tasks and subjects. Possible modifications in device design, and potential combinations of auditory and tactile input via earmold systems, are discussed.