A tale of two tasks: detecting children's off-task speech in a reading tutor
Wei Chen, Jack Mostow · 2011
How can an automated tutor detect children’s off-task utterances? To answer this question, we trained SVM classifiers on a corpus of 495 children’s 36,492 computerassisted oral reading utterances. On a test set of 620 utterances by 10 held-out readers, the classifier correctly detected 88 % of off-task utterances and misclassified 17 % of on-task utterances as off-task. As a test of generality, we applied the same classifier to 20 children’s 410 responses to vocabulary questions. The classifier detected 84 % of off-task utterances but misclassified 57 % of on-task utterances. Acoustic and lexical features helped detected off-task speech in both tasks. Index Terms: off-task speech detection, acoustic feature, lexical feature, children speech 1.