The vehicle interior constitutes the multi-sensory environment of driver and passengers. Beside overall design and execution, materials and its surfaces 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 based on 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 a surface, touch-sounds have been disregarded so far. In various cases, these contact sounds are clearly audible. As essential sound responses to haptic activity, they can degrade perceived quality. A method has been developed for a standardized generation of touch-sounds. It includes simulation of a realistic finger force, touch area and sliding velocity. Sounds generated on numerous steering wheel materials have been recorded. The 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 was 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. This enables the choice of materials with maximized multi-sensory harmony.
