Omnidirectional Haptic Guidance for the Hearing Impaired to Track Sound Sources

We developed a hearing assistance system that enables hearing-impaired people to track the horizontal movement of a single sound source. The movement of the sound source is presented to the subject by vibrating vibrators on both shoulders according to the distance to and direction of the sound source, which are estimated from the acoustic signals detected by microphones attached to both ears. We presented the direction of and distance to the sound source to the subject by changing the ratio of the intensity of the two vibrators according to the direction and by increasing the intensity the closer the person got to the sound source. The subject could recognize the approaching sound source as a change in the vibration intensity by turning their face in the direction where the intensity of both vibrators was equal. The direction of the moving sound source can be tracked with an accuracy of less than 5° when an analog vibration pattern is added to indicate the direction of the sound source. By presenting the direction of the sound source with high accuracy, it is possible to show subjects the approach and departure of a sound source.

Wearable Hearing Assist System to Provide Hearing-Dog Functionality

This study developed a wearable hearing-assist system that can identify the direction of a sound source while using short-term interaural time differences (ITDs) of sound pressure and convey the sound source direction to a hearing-impaired person via vibrators that are attached to his or her shoulders. This system, which is equipped with two microphones, could dynamically detect and convey the direction of front, side, and even rear sound sources. A male subject was able to turn his head toward continuous or intermittent sound sources within approximately 2.8 s when wearing the developed system. The sound source direction is probably overestimated when the interval between the two ears is smaller. When the subject can utilize vision, this may help in tracking the location of the target sound source, especially if the target comes into view, and it may shorten the tracking period.