This paper introduces novel visuo-haptic coupling techniques dedicated to the rendering of contact with objects in virtual reality (VR) using ultrasound mid-air haptics (UMH). More specifically, our objective is to propose various visual and haptic feedback mechanisms for enhancing user perception of interpenetration during interactions with virtual objects. We conducted user studies to evaluate combinations of four visual feedback techniques and three UMH-based haptic techniques, comparing their effects on user experience and contact accuracy. Through the studies, we identified that feedback schemes combining ghost hand visual cues with shrinking circle haptics yield the most intuitive and precise contact perception, while more subtle cues were subjectively preferred. These findings offer insights for advancing user experience and interaction quality in immersive VR environments.