  Making and distributing audio recordings of lectures is cheap and technically
straightforward, and these recordings represent an underexploited teaching
resource. We explore the reasons why such recordings are not more used; we
believe the barriers inhibiting such use should be easily overcome. Students
can listen to a lecture they missed, or re-listen to a lecture at revision
time, but their interaction is limited by the affordances of the replaying
technology. Listening to lecture audio is generally solitary, linear, and
disjoint from other available media.
  In this paper, we describe a tool we are developing at the University of
Glasgow, which enriches students' interactions with lecture audio. We describe
our experiments with this tool in session 2012--13. Fewer students used the
tool than we expected would naturally do so, and we discuss some possible
explanations for this.
