We describe a system which simulates in real-time the auditory and haptic sensation of walking on different surfaces. The system is based on physical models, that drive both the haptic and audio synthesizers,
and a pair of shoes enhanced with sensors and actuators. In a discrimination experiment, subjects were asked to recognize the different simulated surfaces they were exposed to with uni-modal (auditory or haptic) and bi-modal (auditory and haptic) cues. Results show that subjects perform the recognition task
better when using auditory feedback versus haptic feedback. The combination of auditory and haptic feedback only in some conditions significantly enhances recognition.