What's that sound? Distance determination and aperture passage from ultrasound echoes

Abstract

Purpose. Individuals with visual impairment have difficulty detecting obstacles that are above waist height. A prototype device was developed to allow individuals to hear ultrasound reflections off environmental obstacles. The purpose of this research was to evaluate novices' ability to evaluate distance and pass through apertures using this device.

Method. The first experiment evaluated the ability to judge the distance from a wall using the ultrasound system as compared to using auditory echolocation. The second examined time for passage, centreline accuracy and angle of rotation through different sized apertures.

Results. Distance judgement was found to be better with audified ultrasound than with auditory echolocation. When passing through apertures, audified ultrasound enabled centreline precision similar to that of vision, but individuals did not rotate their shoulders while passing through suggesting that more practice is necessary to combine perceptive information with proprioceptive action.

Conclusions. The ability to judge distance and navigate through an environment with obstacles using a device which audifies ultrasound was shown to be better than using auditory echolocation, but not as effective as vision. This device will allow individuals with visual impairments to better detect and avoid environmental obstacles.

Keywords:

• Ultrasound
• assistive technology
• device
• audification
• visually impaired
• avoidance
• apertures

Acknowledgements

We thank George Dodd of the University of Auckland's Acoustic Research Centre who generously allowed the testing to be conducted in the anechoic chamber. We also thank Gian Schmid who aided in the set-up of equipment and insight into how the experiments should be performed. Finally, the participants who gave their time should also be thanked.