  Peer-led team learning (PLTL) is a model for teaching STEM courses where
small student groups meet periodically to collaboratively discuss coursework.
Automatic analysis of PLTL sessions would help education researchers to get
insight into how learning outcomes are impacted by individual participation,
group behavior, team dynamics, etc.. Towards this, speech and language
technology can help, and speaker diarization technology will lay the foundation
for analysis. In this study, a new corpus is established called CRSS-PLTL, that
contains speech data from 5 PLTL teams over a semester (10 sessions per team
with 5-to-8 participants in each team). In CRSS-PLTL, every participant wears a
LENA device (portable audio recorder) that provides multiple audio recordings
of the event. Our proposed solution is unsupervised and contains a new online
speaker change detection algorithm, termed G 3 algorithm in conjunction with
Hausdorff-distance based clustering to provide improved detection accuracy.
Additionally, we also exploit cross channel information to refine our
diarization hypothesis. The proposed system provides good improvements in
diarization error rate (DER) over the baseline LIUM system. We also present
higher level analysis such as the number of conversational turns taken in a
session, and speaking-time duration (participation) for each speaker.
