Words matter

We investigate automatic detection of teacher questions from audio recordings collected in live classrooms with the goal of providing automated feedback to teachers. Using a dataset of audio recordings from 11 teachers across 37 class sessions, we automatically segment the audio into individual teacher utterances and code each as containing a question or not. We train supervised machine learning models to detect the human-coded questions using high-level linguistic features extracted from automatic speech recognition (ASR) transcripts, acoustic and prosodic features from the audio recordings, as well as context features, such as timing and turn-taking dynamics. Models are trained and validated independently of the teacher to ensure generalization to new teachers. We are able to distinguish questions and non-questions with a weighted F1 score of 0.69. A comparison of the three feature sets indicates that a model using linguistic features outperforms those using acoustic-prosodic and context features for question detection, but the combination of features yields a 5% improvement in overall accuracy compared to linguistic features alone. We discuss applications for pedagogical research, teacher formative assessment, and teacher professional development.