This paper explores the use of a physics-based sound model of continuous contact for auditory display in interactive settings. An audio-visual interactive display is developed in which the sound model is controlled by the user's gestures. The display is used to investigate to what extent audition can substitute for haptic feedback in conveying perception of inertial properties of a manipulated object. In a first experiment the audio-visual display is controlled through a standard pointing device (a marble mouse, or trackball). A second experiment uses a tangible object and a computer vision system that tracks the object motion. Early results suggest that the perception of effort is a cross-modal phenomenon in which auditory feedback plays a relevant role.