One challenge for music educators is to find techniques to help students "listen across time" to the examples they are assigned to study and to stay focused on a piece as they listen. Measurement tools to assess music listening have a long history, ranging from very simple to very complex, and very dated to very recent. This article traces the development of the Continuous Response Digital Interface (CRDI) device and reviews its use in music education research, with suggestions for how general music teachers can apply this research in their classrooms. (Contains 1 figure and 26 notes.)