Interactions with physical objects usually evoke sounds, i.e., audi-tory feedback that depends on the interacting objects (e.g., table,hand, or pencil) and interaction type (e.g., tapping or scratching).The continuous real-time adaptation of sound during interactionenables the manipulation/refinement of perceived characteristics(size, material) of physical objects. Furthermore, when controlledby unrelated external data, the resulting ambient sonifications cankeep users aware of changing data. This article introduces the con-cept ofplausibilityto the topic of auditory augmentations of phys-ical interactions, aiming at providing an experimentation platformfor investigating surface-based physical interactions, understand-ing relevant acoustic cues, redefining these via auditory augmenta-tion / blended sonification and particularly to empirically measurethe plausibility limits of such auditory augmentations. Besidesconceptual contributions along the trade-off between plausibilityand usability, a practical experimentation system is introduced, to-gether with a very first qualitative pilot study.