Summary: We introduced in [Commun. Partial Differ. Equations 38, No. 7-9, 1492–1518 (2013; Zbl 1274.35420)] a method to locate discontinuities of a wave speed in dimension 2 from acoustic boundary measurements modeled by the hyperbolic Neumann-to-Dirichlet operator. Here we extend the method for sound hard obstacles in arbitrary dimension. We present numerical experiments with simulated noisy data suggesting that the method is robust against measurement noise.