A social robot system for modeling children's word pronunciation

Autonomous educational social robots can be used to help promote literacy skills in young children. Such robots, which emulate the emotive, perceptual, and empathic abilities of human teachers, are capable of replicating some of the benefits of one-on-one tutoring from human teachers, in part by leveraging individual student's behavior and task performance data to infer sophisticated models of their knowledge. These student models are then used to provide personalized educational experiences by, for example, determining the optimal sequencing of curricular material. In this paper we introduce an integrated system for autonomously analyzing and assessing children's speech and pronunciation in the context of an interactive word game between a social robot and a child. We present a novel game environment and its computational formulation, an integrated pipeline for capturing and analyzing children's speech in real-time, and an autonomous robot that models children's word pronunciation via Gaussian Process Regression (GPR), augmented with an Active Learning protocol that informs the robot's behavior. We show that the system is capable of autonomously assessing children's pronunciation ability, with ground truth determined by a post-experiment evaluation by human raters. We also compare phoneme- and word-level GPR models and discuss trade-offs of each approach in modeling children's pronunciation. Finally, we describe and analyze a pipeline for automatic analysis of children's speech and pronunciation, including an evaluation of SpeechAce as a tool for future development of autonomous, speech-based language tutors.