Abstract:
There are approximately 285 million visually impaired and blind persons worldwide. The primary means of navigation, white canes and guide dogs, can only provide limited environmental understanding and are significantly lacking feedback for obstacles that are present above ground level. Studies have shown that over 50% of those with visually impairment have significant head collisions yearly. This thesis covers the continuation of research into the AUDEO (Audification of Ultrasound for Detection of Environmental Obstacles) device that uses ultrasonic echolocation to assist a visually impaired user navigate through unfamiliar environments by providing an auditory feedback. We aim to research how the redesign of the earpieces, in accordance to hearing aid design, enables higher retention of the spectral cues provided by the pinna which contribute to sound localisation. Furthermore this research will look to cover how the AUDEO device operates outside of anechoic conditions to represent the realworld environment the device will be used. A prototype AUDEO device was developed with an earpiece modelled on the ‘In The Ear’ (ITE) style hearing aid. This redesign allowed fitting of the ultrasound receivers deeper within the ear. To evaluate the affect of the redesigned earpieces, a group of sighted, blindfolded participants undertook three tasks, horizontal and vertical sound source localisation and dynamic target localisation. To adjudge the performance of the participants, motion capture techniques have been simplified, adapted and implemented to track their detailed reactions in real time. The redesign of the AUDEO device has resulted in improved vertical localisation ability from the participants, without detracting from the horizontal localisation potential. Testing has also demonstrated that the AUDEO device provides useful information under realworld, echoic conditions, which are consistent with results found under anechoic conditions. Testing has also demonstrated how the AUDEO device can detect a range of obstacles operating in echoic conditions. Variations in auditory feedback exhibit a potential for more detailed differentiation and interpretation of obstacles for an experienced user. I believe the evidence of this investigation supports the continued research and development of the AUDEO device as a viable means of navigation for the visually impaired.