We consider time-harmonic wave scattering from an inhomogeneous isotropic medium supported in a bounded domain $${\Omega \subset \mathbb{R}^N}$$ (N ≥ 2). In a subregion $${D \Subset \Omega}$$ , the medium is supposed to be lossy and have a large mass density. We study the asymptotic development of the wave field as the mass density ρ → + ∞ and show that the wave field inside D will decay exponentially while the wave filed outside the medium will converge to the one corresponding to a sound-hard obstacle $${D \Subset \Omega}$$ buried in the medium supported in $${\Omega \backslash \overline{D}}$$ . Moreover, the normal velocity of the wave field on ∂ D from outside D is shown to be vanishing as ρ → + ∞. We derive very accurate estimates for the wave field inside and outside D and on ∂ D in terms of ρ, and show that the asymptotic estimates are sharp. The implication of the obtained results is given for an inverse scattering problem of reconstructing a complex scatterer.