“…The spread of English as the main global language for education and commerce is continuing, and there is a strong interest in developing assessment systems that can automatically score spontaneous speech from non-native speakers with the goals of reducing the burden on human raters, improving reliability, and generating feedback that can be used by language learners Higgins et al, 2011). Various features related to different aspects of speaking proficiency have been explored, such as features for pronunciation, prosody, and fluency (Cucchiarini et al, 2002;Chen et al, 2009;Cheng, 2011;Higgins et al, 2011), as well as features for vocabulary, grammar, and content Chen and Zechner, 2011;Chen and Zechner, 2011;Xie et al, 2012;Qian et al, 2016).…”