There are approximately 285 million visually impaired and blind persons worldwide who require some form of assistance during travel. Primary mobility devices including white canes and guide dogs can be used for mobility and detection of obstacles that are below waist height, but do not provide feedback for obstacles that are above the waist. Studies have shown that over 50% of individuals with visual impairment have head collisions on an annual basis. The Audification of Ultrasound for the Detection of Environmental Obstacles (AUDEO) device is a secondary mobility device developed to enable individuals with visual impairment to detect obstacles that are above waist height. This paper provides an introduction to the AUDEO device and the concepts of sound localisation and echolocation. It discusses two iterations of the device in an attempt to increase usability and provides some feedback from a blind user.