Spatial Orientation Using Echolocation — Characterising Signals for Downconversion

Abstract

Individuals with visual impairments sometimes use echolocation for spatial orientation and obstacle detection. An advantage to echolocation is the ability to determine the location of obstacles without physical contact. Echolocation has essentially become obsolete with the increase in environmental noise. If echolocation could be performed at ultrasound and downconverted directly to the auditory domain, visually impaired travellers may be better able to spatially orient. As a first step in this project, we needed to determine auditory signals that could have the potential to allow us to extract meaningful spatial information from the environment. To do this, we evaluated different possible clicks for obstacle detection, examined the ability to determine wall distance with low and high frequency sounds, and finally we used low and high frequency sounds to quantify feedback echoes as a spatial environment changes. This preliminary work showed that echoes that are carried on a higher frequency carrier can be downconverted to produce similar signals to those produced when echoed in the auditory domain directly.