Using bidirectional lstm recurrent neural networks to learn high-level abstractions of sequential features for automated scoring of non-native spontaneous speech. - Zhou Yu 005; Vikram Ramanarayanan; David Suendermann-Oeft; Xinhao Wang; Klaus Zechner; Lei Chen 004; Jidong Tao; Aliaksei Ivanou; Yao Qian (ASRU, 2015)