Collaborative learning with recorded lectures can be supported by allowing users to anchor notes in the documents and exchange them with others. While the traditional modality for annotation and discussion is text, there are a number of reasons in favor of supporting other modalities as well. We present an extension of a lecture-on-demand annotation and discussion system that allows learners to use spoken notes. Our main focus is on the development of a suitable user interface that facilitates the retrieval of speech data employing signal-processing algorithms while at the same time being simple and easy to use.