Echolocating with Ultrasound: A Usability Analysis

Individuals who are totally blind do not have access to visual stimuli, thus one must account for other relationships with nature that provide information to enable effective locomotion and travel. Typically a primary mobility aid such as a long, white cane or a guide dog are used, but these are unable to detect obstacles that are not ground based including tree branches, windows that open outward and wall mounted bookcases. A device known as the AUDEO (audification of ultrasound for the detection of environmental echoes) has been developed as a means to providing information about obstacles above waist height to people with visual impairment. This is expected to be used in addition to a primary mobility aid, but intended to give the individual more confidence in travelling in unknown environments where head high obstacles may exist. Several usability issues have been previously reported and it was suggested that the device must be miniaturised to enable more effective localisation. This paper discusses the redesign of the earpieces, in accordance with hearing aid design, to enable higher retention of the spectral cues provided by the pinna that contribute to sound localisation, specifically vertical localisation. The 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. Vertical localisation testing of blindfolded sighted individuals found that the ability to localise in the vertical direction was increased with the miniaturised version