Identification of Physical Factors Contributing to Hardness Perception of Objects during Indirect Tapping using White Canes

Abstract

Visually impaired people widely use white canes to obtain information from the surrounding environment and thereby walk alone. Clarifying the information presented by current white canes could enable the development of a new white cane with improved usability. Previous studies have reported that the visually impaired can better perceive the hardness of objects by using both hearing and tactile sensations when indirectly tapping objects using the white cane. The white cane and objects vibrate at the resonance frequency when they are tapped. The vibration of the white cane is expected to be detected through tactile sensations, and that of objects is converted into acoustic information and is detected through hearing. In this study, we identified the physical factors contributing to the hardness perception of objects during indirect tapping using white canes. Measurements of the frequency characteristics of the vibration and acoustic information revealed that the similarity of frequency characteristics for different hardness values of objects was lower for acoustic information than for vibration information. This result supports previous study results that reported that hearing is dominant in indirect tapping using white canes.