Water is fluid and changeable, its colour and shape are determined by its environment. For example, deep and shallow water require very different physical simulations [Darles et al. 2011]. Yet humans effortlessly discriminate between water and non-water: there must be simple and unique perceptual features making discrimination possible. We are conducting an empirical study of water recognition and here report the preliminary results.

This study examines methods for displaying distance information to blind travellers using sound, focussing on abstractions of methods currently used in commercial Electronic Travel Aids (ETAs). Ten blind participants assessed three sound encodings commonly used to convey distance information by ETAs: sound frequency (Pitch), Ecological Distance (ED), and temporal variation or Beat Rate (BR). Response time and response correctness were chosen for measures.