We describe a system that can provide combined auditory and haptic sensations that arise while walking on different grounds. The simulation is based on a physical model that drives both haptic transducers embedded in sandals and headphones. The model is able to represent walking interactions with solid surfaces that can creak, be covered with crumpling material. The simulation responds to pressure on the floor by a vibrotactile signal felt by the feet. In a preliminary discrimination experiment, 15 participants were asked to recognize four different surfaces in a list of sixteen possibilities and under three different conditions, haptics only, audition only and combined haptic-audition. The results indicate that subjects are able to recognize most of the stimuli in the audition only condition, and some of the material properties such as hardness in the haptics only condition. The combination of auditory and haptic cues does not significantly improve recognition. Key words: physica...