Effects of Material Touch Sounds on Perceived Quality of Surfaces

Materials for the vehicle interior are of specific interest to the customer. They are not only needed to fulfil technical functions, but are in direct focus of the customer’s perception. The perceived quality is a function of all sensory data collected by the human perceptual system: Surfaces express design intent and craftsmanship by their visual appearance. Haptic features supervene when materials are touched. And even smell has an influence on the perception of ambience. Although sound is generated nearly every time when fingers slide across the surface, touch sounds have been disregarded so far. In order to address this issue, a method has been developed for standardized generation of touch sounds. It includes simulation of realistic finger force, touch area and sliding velocity. Sounds generated on typical flat specimen of steering wheel materials have been recorded. Sounds were played back to participants under exclusive auditory conditions. The influence of psycho-physical parameters and iconic sound features on perceived quality has been investigated. Furthermore, the interaction of sound sensation with visual and haptic features could be studied. Results demonstrate that the sound excited by fingers sliding across a surface contains essential information about the nature and the quality of materials applied. As an example, the auditory roughness can modify the perceived haptic roughness of a surface. A consequent consideration of surface touch sounds enables choice of materials with maximized multi-sensory harmony.