Think alouds in literacy:
When doing a think aloud, the person (teacher or student) narrates their thoughts, observations, questions, etc. while reading. This provides insight into their cognitive processes while also motivating them to more deeply consider the text being studied. As a teaching tool, it allows the teacher to model the sorts of engagements with a text that we hope our students can use as well as serve as an informal assessment of the students' cognitive processes.
Think alouds in music:
Think alouds can be conducted similarly within the music classroom either to model critical listening and reading or to illuminate the students' internal cognitive processes.
When listening to a piece of music (this could include performances by the ensemble as well as model recordings), the teacher narrates what they hear as it goes by in real time. This could include the teacher's observations of the ensemble's execution (e.g. "The clarinets seem to be struggling with crossing the break on that run) or the teacher's own reactions (e.g. "When the timpani builds on that crescendo, I really feel anxious, like something is about to happen."). Similarly, the teacher could place a score on a projector and talk through their score study (e.g. "The music is really dense at rehearsal mark D-we'll need to really pay attention to our balance so not to overwhelm the melody") in a way that we would hope students would.
Students can likewise conduct think alouds. When listening to a recording, small groups of students could lead the class through the listening activity, both reacting to the music and the observations of other students. Similar to the score reading exercise above, students could talk through their observations of their individual parts or an entire score, focusing both on what they anticipate to encounter within the piece as well as questions that they can address as they move further.