In this paper, a physics-based framework is presented to visualize the human tongue deformation. The tongue is modeled with the Finite Element Method (FEM) and driven by the motion capture data gathered during speech production. Several novel deformation visualization techniques are presented for in-depth data analysis and exploration. To reveal the hidden semantic information of the tongue deformation, we present a novel physics-based volume segmentation algorithm. This is accomplished by decomposing the tongue model into segments based on its deformation pattern with the computation of deformation subspaces and fitting the target deformation locally at each segment. In addition, the strain energy is utilized to provide an intuitive low-dimensional visualization for the high-dimensional sequential motion. Energy-interpolation-based morphing is also equipped to effectively highlight the subtle differences of the 3D deformed shapes without any visual occlusion. Our experimental results and analysis demonstrate the effectiveness of this framework. The proposed methods, though originally designed for the exploration of the tongue deformation, are also valid for general deformation analysis of other shapes.