Hardness Perception Based on Dynamic Stiffness in Tapping.

A human can judge the hardness of an object based on the damped natural vibration caused by tapping the surface of the object using a fingertip. In this study, we investigated the influence of the dynamic characteristics of vibrations on the hardness perceived by tapping. Subjectively reported hardness values were related to the dynamic stiffness of several objects.

Perceived Hardness through Actual and Virtual Damped Natural Vibrations.

Humans perceive hardness of objects from damped natural vibrations by tapping their surfaces. We investigated the roles of six parameters characterizing the vibration in virtual and real environments. The effects of some parameters differed between the two environments.